#include <stdio.h>

int i, j, round, N;

int main()
{
	freopen("tije.in", "r", stdin);
	scanf("%d", &N);

	freopen("tije.out", "w", stdout);

    for (round = 1; round < N; round++)
	{
		for (j = 1; j <= round; j++)
			printf("%d %d\n", N, N + 1);

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

			printf("%d %d\n", i, N + 1);
		}

		for (i = 1; i <= N - round; i++)
			printf("%d %d\n", round, round + i);

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

	return 0;
}