import decimal

import sys

from decimal import Decimal



sys.setrecursionlimit(10 ** 7)

rl = sys.stdin.readline





def solve():

    A, B = rl().split()

    ans = Decimal(A) * Decimal(B)

    ans = ans.quantize(Decimal('0'), rounding=decimal.ROUND_FLOOR)

    print(ans)





if __name__ == '__main__':

    solve()

import sys



sys.setrecursionlimit(10 ** 7)

rl = sys.stdin.readline





def solve():

    A, B = rl().split()

    A = int(A)

    B = B.split('.')

    B = int(B[0] + B[1])

    ans = A * B // 100

    print(ans)





if __name__ == '__main__':

    solve()

import decimal
import sys
from decimal import Decimal

sys.setrecursionlimit(10**7)
rl = sys.stdin.readline


def solve():
    A, B = rl().split()
    ans = Decimal(A) * Decimal(B)
    ans = ans.quantize(Decimal("0"), rounding=decimal.ROUND_FLOOR)
    print(ans)


if __name__ == "__main__":
    solve()

import sys

sys.setrecursionlimit(10**7)
rl = sys.stdin.readline


def solve():
    A, B = rl().split()
    A = int(A)
    B = B.split(".")
    B = int(B[0] + B[1])
    ans = A * B // 100
    print(ans)


if __name__ == "__main__":
    solve()

-import decimal -from decimal import Decimal -    ans = Decimal(A) * Decimal(B) -    ans = ans.quantize(Decimal("0"), rounding=decimal.ROUND_FLOOR) +    A = int(A) +    B = B.split(".") +    B = int(B[0] + B[1]) +    ans = A * B // 100