#include <iostream>

using namespace std;
int main()
{
    int num, i, j, prime;
    cout << "Enter the upper limit :";
    cin >> num;

    int prevPrimeNum=-1;

    for (i = 3;i <= num;i++)
    {
        prime = 1;
        for (j = 2;j < i;j++)
        {
            if (i%j == 0)
            {
                prime = 0;
                break;
            }
        }
        if (prime == 1) {
            if (i - prevPrimeNum == 2)
                cout << prevPrimeNum << " " << i << endl;
            prevPrimeNum = i;
        }
    }

}