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

int main(void)
{
  ll a;
  long double b, c;
  scanf("%lld%lf", &a, &b);
  c = a * b;
  printf("%lld\n", (ll)c);
  return 0;
}
