#include <stdio.h>
int main () {
    long long a;
    double b;
    scanf("%lld %lf",&a,&b);
    // printf("%lf %lf\n",a, b);
    long long c = (long long int)(b*100);
    // printf("%lf %lf %lf\n",a, b, ans);
    printf("%lld",a*c/100);
}