add Mailman easy solution

Author: jakovmitrovski

medium300/MailmanEasy.java

@@ -0,0 +1,16 @@
+package medium300;
+
+public class MailmanEasy {
+    public String totalHouses(int H, int W) {
+
+        long x = ((long) H * W);
+
+        if (H == 1 && W > 2 || W == 1 && H > 2)
+            return "0";
+        else if (H % 2 == 0 || W % 2 == 0)
+            return String.valueOf(x);
+
+        return "0";
+
+    }
+}