#include<stdio.h>
#include<stdlib.h>
typedef long long ll;
int main(void)
{
  ll n,cn,ans=0,a;
  double b;
  scanf("%lld %lf",&a,&b);
  cn=(ll)(100.0*b);
  ans=a*cn/100;
  printf("%lld\n",ans);
  return 0;

}