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

ll a;
double b;

int main(){
  scanf("%lld%lf",&a,&b);

  ll tmp=b*100;
  ll ans=a*tmp/100;
  printf("%lld\n",ans);
  
  return 0;
}
