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

int main()
{
  long long A,C;
  long double B;
  scanf("%lld",&A);
  scanf("%Lf",&B);
  B*=100;
  B=round(B);
  C=A*B/100;
  printf("%lld\n",C);
  return 0;
}


