#include<stdio.h>

int main(void){
    long long int A;
    double B;
    int hun_B;

    long long int ans;

    scanf("%lld %lf", &A, &B);

    hun_B = 100*B;

    ans = (int)(A*hun_B / 100);
    printf("%lld\n", ans);

    return 0;

}