n = input()
n = int(n)
if n >= 90:
    print(n * 3)
elif 80 >= n >= 90:
    print(n * 2)
elif 70 >= n >= 80:
    print(n)
elif n <= 70:
    print("50")
elif n >= 90:
    print(n * 3)

/**************************************************************
	Problem: 1300
	User: xiaomingze
	Language: Python
	Result: Wrong Answer
****************************************************************/