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')
    

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