#include <malloc.h>
#include <math.h>
#include <stdio.h>
#include <string.h>

//ABC169C
int main(){
    long long a;
    double  b;
    scanf("%ld %Lf",&a,&b);
    long double c=a*b;
    long int d = c;
    printf("%ld\n",d);
 
    return 0;
}