#include <iostream>
#include <fstream>

using namespace std;

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

int n, i, j, k;

void rezolva() {
    for (k = n - 1; k >= 1; k--) {
        for (i = n; i >= 1; i--)
            for (j = 1; j <= k; j++)
                g << i << ' ' << i + 1 << '\n';
        for (i = 1; i <= k; i++) g << n + 1 << ' ' << 1 << '\n';
    }
}

int main() {
    f >> n;
    rezolva();
    return 0;
}