#include <stdio.h>

int main(void){
    long long int a,ansa;
    double b;
    int  c;
    //c=(double)100*b;
    
    scanf("%lld %lf",&a,&b);
    c=(double)100*b +0.001;
    //c=(double)100.00*b;
    //printf("%d",c);
    ansa=(a*c)/100;
    
    printf("%lld\n",ansa);
    return 0;
}