https://www.luogu.com.cn/problem/P1422
"""
P1422 小玉家的电费
https://www.luogu.com.cn/problem/P1422
"""
a=int(input())
if a<151:
b=a*0.4463
print("%.1f"%b)
if a>150 and a<401:
b=(a-150)*0.4663
c=150*0.4463+b
print("%.1f"%c)
if a>400:
b=(a-400)*0.5663
c=150*0.4463+(400-150)*0.4663+b
print("%.1f"%c)
