import decimal

def resolve():    



    a, b = list(map(decimal.Decimal, input().split()))

    print((a * b // 1))

    

if __name__ == "__main__":

    resolve()


def resolve():

    a, b = input().split()

    a = int(a)

    b = int(float(b) * 100 + .5)

    

    ans = a*b

    print((ans//100))

if __name__ == "__main__":

    resolve()
import decimal


def resolve():
    a, b = list(map(decimal.Decimal, input().split()))
    print((a * b // 1))


if __name__ == "__main__":
    resolve()

def resolve():
    a, b = input().split()
    a = int(a)
    b = int(float(b) * 100 + 0.5)
    ans = a * b
    print((ans // 100))


if __name__ == "__main__":
    resolve()

-import decimal - - -    a, b = list(map(decimal.Decimal, input().split())) -    print((a * b // 1)) +    a, b = input().split() +    a = int(a) +    b = int(float(b) * 100 + 0.5) +    ans = a * b +    print((ans // 100))