# import sys

# readline = sys.stdin.readline

# generator = (readline().strip() for _ in range(N))



# N, M = map(int, input().split())

# As = list(map(int, input().split()))

# queries = (input() for _ in range(N))





def solve():

    N, M = input().split()



    n = int(N)

    f = float(M)

    m = int(f * 100 + 0.1)

    ans = n * m // 100



    return ans





def main():

    print((solve()))





if __name__ == "__main__":

    main()

def solve():

    N, M = input().split()



    n = int(N)

    m = int(M.replace('.', ''))



    return n * m // 100





def main():

    print((solve()))





if __name__ == "__main__":

    main()

# import sys
# readline = sys.stdin.readline
# generator = (readline().strip() for _ in range(N))
# N, M = map(int, input().split())
# As = list(map(int, input().split()))
# queries = (input() for _ in range(N))
def solve():
    N, M = input().split()
    n = int(N)
    f = float(M)
    m = int(f * 100 + 0.1)
    ans = n * m // 100
    return ans


def main():
    print((solve()))


if __name__ == "__main__":
    main()

def solve():
    N, M = input().split()
    n = int(N)
    m = int(M.replace(".", ""))
    return n * m // 100


def main():
    print((solve()))


if __name__ == "__main__":
    main()

-# import sys -# readline = sys.stdin.readline -# generator = (readline().strip() for _ in range(N)) -# N, M = map(int, input().split()) -# As = list(map(int, input().split())) -# queries = (input() for _ in range(N)) -    f = float(M) -    m = int(f * 100 + 0.1) -    ans = n * m // 100 -    return ans +    m = int(M.replace(".", "")) +    return n * m // 100