#include <cstdio>
int main()
{
    int n, k, i, j;
    freopen("tije.in", "r", stdin);
    freopen("tije.out", "w+", stdout);
    scanf("%d", &n);
    for (k = n - 1; k; --k) {
        for (i = n; i; --i)
            for (j = 0; j != k; ++j) printf("%d %d\n", i, i + 1);
        for (j = 0; j != k; ++j) printf("%d 1\n", n + 1);
    }
    return 0;
}