#include <cstdio>

using namespace std;

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++)
                printf("%d %d\n", i, i + 1);
        for (i = 1; i <= k; i++)
            printf("%d 1\n", n + 1);
    }
}

int main() {
    freopen("tije.in","r",stdin);
    freopen("tije.out","w",stdout);
    scanf("%d",&n);
    rezolva();
    return 0;
}