Ex.35_Dog_Years.py

# It is commonly said that one human year is equivalent to 7 dog years. 
# However this simple conversion fails to recognize that dogs reach adulthood in approximately two years. 
# As a result, some people believe that it is better to count each of the first two human years
# as 10.5 dog years, and then count each additional human year as 4 dog years.
# Write a program that implements the conversion from human years to dog years described in the 
# previous paragraph. Ensure that your program works correctly for conversions of less than two human 
# years and for conversions of two or more human years. Your program should display
# an appropriate error message if the user enters a negative number.

human_years = (int(input("Please enter your age: ")))
dog_years = 0
if  human_years < 0:
    print("Please enter only positive numbers.")
elif human_years < 3:
    dog_years = human_years * 10.5
else:
    dog_years = (human_years - 2) * 4
    dog_years += 10.5 * 2

print("Your age in dog years would be: %d" %(dog_years))