import math

import decimal

if __name__ == "__main__":

    a, b = input().split()



    a = decimal.Decimal(a)

    b = decimal.Decimal(b)

    ans = (a * b)

    ans = int(ans)

    print(ans)
import math

if __name__ == "__main__":

    a, b = input().split()



    a = int(a)

    b = float(b)



    b = int(100 * b + 0.4)

    print(((a*b)//100))
import math
import decimal

if __name__ == "__main__":
    a, b = input().split()
    a = decimal.Decimal(a)
    b = decimal.Decimal(b)
    ans = a * b
    ans = int(ans)
    print(ans)

import math

if __name__ == "__main__":
    a, b = input().split()
    a = int(a)
    b = float(b)
    b = int(100 * b + 0.4)
    print(((a * b) // 100))

-import decimal -    a = decimal.Decimal(a) -    b = decimal.Decimal(b) -    ans = a * b -    ans = int(ans) -    print(ans) +    a = int(a) +    b = float(b) +    b = int(100 * b + 0.4) +    print(((a * b) // 100))