from decimal import Decimal,ROUND_DOWN
while True:
    try:
        n=Decimal(input())
        if n<100: x=n*Decimal('0.9')+8
        elif n<=500: x=n*Decimal('0.8')
        else: x=n*Decimal('0.6')
        print(f"${x.quantize(Decimal('0.00'),rounding=ROUND_DOWN)}")
    except EOFError:break