文件目录

#include <iostream>
#include <cmath>
using namespace std;
bool ispri(int n)
{
    if (n < 2)
        return false;
    for (int i = 2; i <= sqrt(n); i++)
        if (n % i == 0)
            return false;
    return true;
}
int main()
{
    int n;
    cin >> n;
    bool f = true;
    for (int i = 3; i <= n; i += 2)
    {
        if (ispri(i) && ispri(i + 2))
        {
            cout << i << " " << i + 2 << endl;
            f = false;
        }
    }
    if (f)
        cout << "empty";
    return 0;
}