diff --git "a/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-16681] \353\223\261\354\202\260.md" "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-16681] \353\223\261\354\202\260.md"
new file mode 100644
index 00000000..93161cc4
--- /dev/null
+++ "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-16681] \353\223\261\354\202\260.md"	
@@ -0,0 +1,98 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+public class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		while(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static final long INF = (long)1e18 + 7;
+	
+	static int N, M, D, E;
+	static List<int[]>[] V;
+	static int[] H;
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+		
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		N = nextInt();
+		M = nextInt();
+		D = nextInt();
+		E = nextInt();
+
+		H = new int[N+1];
+		for(int i=1;i<=N;i++) H[i] = nextInt();
+		
+		V = new List[N+1];
+		for(int i=1;i<=N;i++) V[i] = new ArrayList<>();
+		for(int i=0;i<M;i++) {
+			int a = nextInt(), b = nextInt(), c = nextInt();
+			V[a].add(new int[] {b,c});
+			V[b].add(new int[] {a,c});
+		}
+		
+	}
+	
+	static void solve() throws Exception {
+		
+		long[] A = dijk(1), B = dijk(N);
+		
+		long ans = -INF;
+		for(int i=2;i<N;i++) if(A[i] != INF && B[i] != INF) {
+			ans = Math.max(ans, (long)H[i]*E - D*(A[i]+B[i]));
+		}
+		
+		if(ans == -INF) bw.write("Impossible");
+		else bw.write(ans + "\n");
+		
+	}
+	
+	static long[] dijk(int start) {
+		long[] X = new long[N+1];
+		Arrays.fill(X, INF);
+		X[start] = 0;
+		PriorityQueue<long[]> Q = new PriorityQueue<>((a,b) -> Long.compare(a[0], b[0]));
+		Q.offer(new long[] {0,start});
+		while(!Q.isEmpty()) {
+			long[] now = Q.poll();
+			long d = now[0];
+			int n = (int)now[1];
+			if(d > X[n]) continue;
+			for(int[] e:V[n]) {
+				int i = e[0], c = e[1];
+				if(X[i] > d+c && H[n] < H[i]) {
+					X[i] = d+c;
+					Q.offer(new long[] {X[i],i});
+				}
+			}
+		}
+		return X;
+	}
+	
+}
+
+```
diff --git "a/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-1800] \354\235\270\355\204\260\353\204\267 \354\204\244\354\271\230.md" "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-1800] \354\235\270\355\204\260\353\204\267 \354\204\244\354\271\230.md"
new file mode 100644
index 00000000..f84bc98c
--- /dev/null
+++ "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-1800] \354\235\270\355\204\260\353\204\267 \354\204\244\354\271\230.md"	
@@ -0,0 +1,91 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		while(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static final int INF = (int)1e9 + 7;
+	
+	static int N, P, K;
+	static List<int[]>[] V;
+	static int[][] D;
+	static PriorityQueue<int[]> Q;
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+		
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		N = nextInt();
+		P = nextInt();
+		K = nextInt();
+		V = new List[N+1];
+		for(int i=1;i<=N;i++) V[i] = new ArrayList<>();
+		for(int i=0;i<P;i++) {
+			int a = nextInt(), b = nextInt(), c = nextInt();
+			V[a].add(new int[] {b,c});
+			V[b].add(new int[] {a,c});
+		}
+		
+		D = new int[N+1][K+1];
+		for(int i=1;i<=N;i++) Arrays.fill(D[i], INF);
+		Q = new PriorityQueue<>((a,b) -> a[0]-b[0]);
+		
+	}
+	
+	static void solve() throws Exception {
+		
+		D[N][0] = 0;
+		Q.offer(new int[] {0,N,0});
+		int ans = INF;
+		while(!Q.isEmpty()) {
+			int[] now = Q.poll();
+			int d = now[0], n = now[1], k = now[2];
+			if(d > D[n][k]) continue;
+			if(n == 1) {
+				ans = Math.min(ans, d);
+				break;
+			}
+			for(int[] e:V[n]) {
+				int i = e[0], c = Math.max(d, e[1]);
+				// 안 쓰는 경우
+				if(D[i][k] > c) {
+					D[i][k] = c;
+					Q.offer(new int[] {c,i,k});
+				}
+				// 쓰는 경우
+				if(k<K && D[i][k+1] > d) {
+					D[i][k+1] = d;
+					Q.offer(new int[] {d,i,k+1});
+				}
+			}
+		}
+		bw.write((ans == INF ? -1 : ans) + "\n");
+		
+	}
+	
+}
+```
diff --git "a/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-18119] \353\213\250\354\226\264 \354\225\224\352\270\260.md" "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-18119] \353\213\250\354\226\264 \354\225\224\352\270\260.md"
new file mode 100644
index 00000000..aeca95ba
--- /dev/null
+++ "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-18119] \353\213\250\354\226\264 \354\225\224\352\270\260.md"	
@@ -0,0 +1,75 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		while(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static int N, M;
+	static int[] A, O;
+	static int[] T;
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+		
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		N = nextInt();
+		M = nextInt();
+		A = new int[N];
+		T = new int[135];
+		int c = 0;
+		for(char i='a';i<='z';i++) {
+			if(i=='a' || i=='e' || i=='i' || i=='o' || i=='u') T[i] = -1;
+			else T[i] = c++;
+		}
+		
+		for(int i=0;i<N;i++) {
+			for(char j:br.readLine().toCharArray()) if(T[j] != -1) A[i] |= (1<<T[j]);
+		}
+		
+		O = new int[N];
+		for(int i=0;i<N;i++) O[i] = A[i];
+		
+	}
+	
+	static void solve() throws Exception {
+		
+		int ans = N;
+		for(int i=0;i<M;i++) {
+			int o = nextInt();
+			char a = nextToken().charAt(0);
+			for(int j=0;j<N;j++) if((O[j] & (1<<T[a])) != 0) {
+				if(A[j] == O[j]) ans--;
+				A[j] ^= (1<<T[a]);
+				if(A[j] == O[j]) ans++;
+			}
+			bw.write(ans + "\n");
+		}
+		
+	}
+	
+}
+```
diff --git "a/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-1911] \355\235\231\352\270\270 \353\263\264\354\210\230\355\225\230\352\270\260.md" "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-1911] \355\235\231\352\270\270 \353\263\264\354\210\230\355\225\230\352\270\260.md"
new file mode 100644
index 00000000..8eada021
--- /dev/null
+++ "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-1911] \355\235\231\352\270\270 \353\263\264\354\210\230\355\225\230\352\270\260.md"	
@@ -0,0 +1,64 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+public class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		while(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static int N, L;
+	static int[][] A;
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+		
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		N = nextInt();
+		L = nextInt();
+		A = new int[N][2];
+		for(int i=0;i<N;i++) for(int j=0;j<2;j++) A[i][j] = nextInt();
+		
+	}
+	
+	static void solve() throws Exception {
+		
+		Arrays.sort(A, (a,b) -> a[0]-b[0]);
+		int ans = 0, next = -1;
+		for(int i=0;i<N;i++) {
+			int s = A[i][0], e = A[i][1];
+			if(next >= e) continue;
+			next = Math.max(s, next);
+			int temp = (e-next-1)/L + 1;
+			ans += temp;
+			next += temp*L;
+		}
+		bw.write(ans + "\n");
+		
+	}
+	
+}
+
+```
diff --git "a/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-23743] \353\260\251\355\203\210\354\266\234.md" "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-23743] \353\260\251\355\203\210\354\266\234.md"
new file mode 100644
index 00000000..01b3423f
--- /dev/null
+++ "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-23743] \353\260\251\355\203\210\354\266\234.md"	
@@ -0,0 +1,69 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+public class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		while(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static int N, M;
+	static List<int[]> E;
+	static int[] r;
+	
+	static int f(int x) {return x==r[x] ? x : (r[x]=f(r[x]));}
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+		
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		N = nextInt();
+		M = nextInt();
+		r = new int[N+1];
+		for(int i=0;i<=N;i++) r[i] = i;
+		E = new ArrayList<>();
+		while(M-->0) E.add(new int[] {nextInt(), nextInt(), nextInt()});
+		for(int i=1;i<=N;i++) E.add(new int[] {0, i, nextInt()});
+		
+	}
+	
+	static void solve() throws Exception {
+		
+		Collections.sort(E, (a,b) -> a[2]-b[2]);
+		int ans = 0;
+		for(int[] e:E) {
+			int a = e[0], b = e[1], c = e[2];
+			int x = f(a), y = f(b);
+			if(x==y) continue;
+			r[x] = y;
+			ans += c;
+		}
+		bw.write(ans + "\n");
+		
+	}
+	
+}
+
+```
diff --git "a/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-3020] \352\260\234\353\230\245\353\262\214\353\240\210.md" "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-3020] \352\260\234\353\230\245\353\262\214\353\240\210.md"
new file mode 100644
index 00000000..79237efc
--- /dev/null
+++ "b/\352\266\214\355\230\201\354\244\200_15\354\243\274\354\260\250/[BOJ-3020] \352\260\234\353\230\245\353\262\214\353\240\210.md"	
@@ -0,0 +1,88 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+public class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		while(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static int[] S;
+	static int N, H;
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+		
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		N = nextInt();
+		H = nextInt();
+		S = new int[H+1];
+		
+	}
+	
+	static void solve() throws Exception {
+		
+		PriorityQueue<Integer> low = new PriorityQueue<>((a,b) -> Integer.compare(a, b));
+		PriorityQueue<Integer> high = new PriorityQueue<>((a,b) -> Integer.compare(b, a));
+		for(int i=0;i<N;i++) {
+			int a = nextInt();
+			if(i%2==0) low.add(a);
+			else high.add(H-a);
+		}
+		
+		int cnt = N/2;
+		for(int i=1;i<H;i++) {
+			while(!low.isEmpty() && low.peek() == i-1) {
+				low.poll();
+				cnt--;
+			}
+			S[i] += cnt;
+		}
+		
+		cnt = N/2;
+		for(int i=H;i>0;i--) {
+			while(!high.isEmpty() && high.peek() == i) {
+				high.poll();
+				cnt--;
+			}
+			S[i] += cnt;
+		}
+		
+		int min = Integer.MAX_VALUE;
+		cnt = 0;
+		for(int i=1;i<=H;i++) {
+			if(S[i] < min) {
+				min = S[i];
+				cnt = 1;
+			}
+			else if(min == S[i]) cnt++;
+		}
+		bw.write(min + " " + cnt);
+		
+	}
+	
+}
+
+```