'''Question: 
Write a Python program to calculate a dog's age in dog's years.
Note: For the first two years, a dog year is equal to 10.5 human years. After that, each dog year equals 4 human years.
'''

# Python code: 

h_age = int(input("Input a dog's age in human years: "))



if h_age < 0:

	print("Age must be positive number.")

	exit()

elif h_age <= 2:

	d_age = h_age * 10.5

else:

	d_age = 21 + (h_age - 2)*4



print("The dog's age in dog's years is", d_age)



'''Output sample: 
Input a dog's age in human years: 12                                                                          

The dog's age in dog's years is 61   

'''