# -*- coding: utf-8 -*-
"""
Created on Wed Apr 4 19:58:38 2018
@author: wdf
"""
x = int(input())#输入
if x<=150:
y=0.4463*x
elif x<=400:
y=0.4463*150+(x-150)*0.4663
else:
y=0.4463*150+(400-150)*0.4663+(x-400)*0.5663
print('%.1f'%y)
"""
Created on Wed Apr 4 19:58:38 2018
@author: wdf
"""
x = int(input())#输入
if x<=150:
y=0.4463*x
elif x<=400:
y=0.4463*150+(x-150)*0.4663
else:
y=0.4463*150+(400-150)*0.4663+(x-400)*0.5663
print('%.1f'%y)