# -*- coding: utf-8 -*-
"""
No.350 d=vt
https://yukicoder.me/problems/no/350

"""
import sys
from sys import stdin
input = stdin.readline


def main(args):
    v, t = input().split()
    t = int(t)
    v = int(v[2:])
    print(v * t // 10000)


if __name__ == '__main__':
    main(sys.argv[1:])