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

using namespace std;

int N;

int main()
{
    freopen("tije.in", "r", stdin);
    freopen("tije.out", "w", stdout);

    scanf("%d\n", &N);

    for ( int cate = N - 1; cate >= 1; --cate )
    {
        for ( int i = 1; i <= cate; ++i )
                printf("1 %d\n", N + 1 );

        for ( int i = 2; i <= N + 1; ++i )
                for ( int j = 1; j <= cate; ++j )
                        printf("%d %d\n", i, i - 1 );
    }

    fclose( stdin );
    fclose( stdout );

    return 0;
}