import sys

from decimal import Decimal



read = sys.stdin.read

readline = sys.stdin.readline

readlines = sys.stdin.readlines

sys.setrecursionlimit(10 ** 9)

INF = 1 << 60





def main():

    A, B = list(map(Decimal, readline().split()))

    print((int(A * B)))



    return





if __name__ == '__main__':

    main()

import sys



read = sys.stdin.read

readline = sys.stdin.readline

readlines = sys.stdin.readlines

sys.setrecursionlimit(10 ** 9)

INF = 1 << 60





def main():

    A, B = readline().split()

    A = int(A)

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

    print((A * B // 100))



    return





if __name__ == '__main__':

    main()

import sys
from decimal import Decimal

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10**9)
INF = 1 << 60


def main():
    A, B = list(map(Decimal, readline().split()))
    print((int(A * B)))
    return


if __name__ == "__main__":
    main()

import sys

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10**9)
INF = 1 << 60


def main():
    A, B = readline().split()
    A = int(A)
    B = int(B.replace(".", ""))
    print((A * B // 100))
    return


if __name__ == "__main__":
    main()

-from decimal import Decimal -    A, B = list(map(Decimal, readline().split())) -    print((int(A * B))) +    A, B = readline().split() +    A = int(A) +    B = int(B.replace(".", "")) +    print((A * B // 100))