#include <bits/stdc++.h>

using namespace std;
ifstream in("tije.in");
ofstream out("tije.out");
int main()
{
    int n, val;
    in >> n;
    for( int q = n-1 ; q > 0; q-- ){
        val = n;
        for( int i = 1 ; i <= n; i++ ){
            for( int j = q; j > 0; j-- )
                out << val << " " << val+1 << endl;
            val--;
        }
        for( int i = 1; i <= q; i++ )
            out << n+1 << " " << 1 << endl;
    }
    return 0;
}