#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    long long A;
    long long ans;
    double Bt;
    int B;
    scanf("%lld", &A);
    scanf("%lf", &Bt);
    B = (int)(100 * Bt);
    ans = B * A;
    ans = (long long)(ans / 100);
    printf("%lld", ans);
    return 0;
}