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

int main(){
  long long int a;
  double ans,b;
    

  scanf("%lld %lf",&a,&b);
  //printf("%lld\n",a);
  //printf("%f\n",b);
  ans = ((double)a)*b;
  printf("%lld\n",(long long int)ans);
  
  return 0;
}