#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 != 0; --k) {
		for (i = n; i != 0; --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);
	}
}