#include <iostream>
#include <fstream>
#include <cstring>
#include <algorithm>

using namespace std;

int N;

int main()
{
    ifstream f("tije.in");
    ofstream g("tije.out");

    f >> N;

    for ( int cate = N - 1; cate >= 1; cate-- )
    {
        for ( int i = N; i >= 1; i-- )
                for ( int j = 1; j <= cate; ++j )
                        g << i << " " << i + 1 << "\n";

        for ( int i = 1; i <= cate; ++i )
                g << N + 1 << " " << 1 << "\n";
    }

    f.close();
    g.close();

    return 0;
}