num = int(input())
price = 0.0
if num<=150:
    price += num*0.4463
else:
    price += 150*0.4463 # 小于150的部分
    num -= 150
    if num<=250:
        price += num*0.4663
    else:
        price += 250*0.4663
        num -= 250
        price += num*0.5663
print(f"{price:.1f}")