#include <bits/stdc++.h>

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