import sys

import decimal

input = lambda: sys.stdin.readline().rstrip()





def solve():

    A, B = input().split()

    A = int(A)

    B = decimal.Decimal(B)

    print((int(A * B)))





if __name__ == '__main__':

    solve()

import sys



input = lambda: sys.stdin.readline().rstrip()





def solve():



    A, B = input().split()

    A = int(A)

    B = B.replace('.', '')

    B = int(B)

    ans = (A * B) // 100

    print(ans)





if __name__ == '__main__':

    solve()

import sys
import decimal

input = lambda: sys.stdin.readline().rstrip()


def solve():
    A, B = input().split()
    A = int(A)
    B = decimal.Decimal(B)
    print((int(A * B)))


if __name__ == "__main__":
    solve()

import sys

input = lambda: sys.stdin.readline().rstrip()


def solve():
    A, B = input().split()
    A = int(A)
    B = B.replace(".", "")
    B = int(B)
    ans = (A * B) // 100
    print(ans)


if __name__ == "__main__":
    solve()

-import decimal -    B = decimal.Decimal(B) -    print((int(A * B))) +    B = B.replace(".", "") +    B = int(B) +    ans = (A * B) // 100 +    print(ans)