#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
typedef long long ll;


int main()
{
    ll a;
    long double b;
    scanf("%lld %Lf",&a,&b);
    
    a=a*b;

    printf("%lld\n",a);

    return 0;
}