n=int(input())
if n>=30:
    s=n
elif n>=20:
    s=n*1.2
elif n>=10:
    s=n*1.5
else:
    s=n*1.8
print('%.1f'%s)

/**************************************************************
	Problem: 1304
	User: admin
	Language: Python
	Result: Accepted
	Time:232 ms
	Memory:34244 kb
****************************************************************/