n = int(input())
if n <= 150:
    a = n * 0.4463
    print(round(a,1))
if n > 150 and n <= 400:
    a = 150 * 0.4463 + (n - 150) * 0.4663
    print(round(a,1))
if n > 400:
    a = 150 * 0.4463 + 250 * 0.4663 + (n - 400) * 0.5663
    print(round(a,1))
/**************************************************************
	Problem: 1463
	User: admin
	Language: Python
	Result: Accepted
	Time:234 ms
	Memory:34480 kb
****************************************************************/