#include<stdio.h>
int main()
{
    unsigned long long int a,d,e;
    double b,c;
    scanf("%llu",&a);
    scanf("%lf",&b);
    b=100*b;
    e=(unsigned long long int)b;
    c=(a*e)/100;
    d=(unsigned long long int)c;
    printf("%llu",d);
    return 0;
}