4948 : 베르트랑 공준 [C++]

#include <iostream>

using namespace std;

int main()
{
 int Input;
 cin >> Input;

 while (Input != 0)
 {
  bool Array[246913];
  int Count = 0;

  for (int i = 0; i < 246913; i++)
  {
   Array[i] = true;
  }

  for (int i = 2; i <= Input; i++)
  {
   for (int j = 2; i * j <= Input * 2; j++)
   {
    if (i * j > Input)
     Array[i*j] = false;
   }
  }

  for (int i = Input + 1; i <= Input * 2; i++)
  {
   if (Array[i])
    Count++;
  }

  cout << Count << endl;

  cin >> Input;
 }
}