#!python3



iim = lambda: list(map(int, input().rstrip().split()))

from decimal import Decimal



def resolve():

    a, b = input().split()

    a = int(a); b = int(b.replace(".", ""))



    print((a*b//100))



if __name__ == "__main__":

    resolve()

#!python3



iim = lambda: list(map(int, input().rstrip().split()))



def resolve():

    a, b = input().split()

    a = int(a); b = int(b.replace(".", ""))



    print((a*b//100))



if __name__ == "__main__":

    resolve()

#!python3
iim = lambda: list(map(int, input().rstrip().split()))
from decimal import Decimal


def resolve():
    a, b = input().split()
    a = int(a)
    b = int(b.replace(".", ""))
    print((a * b // 100))


if __name__ == "__main__":
    resolve()

#!python3
iim = lambda: list(map(int, input().rstrip().split()))


def resolve():
    a, b = input().split()
    a = int(a)
    b = int(b.replace(".", ""))
    print((a * b // 100))


if __name__ == "__main__":
    resolve()

-from decimal import Decimal