#include <stdio.h>

int main()
{
	freopen("tije.in","r",stdin);
	freopen("tije.out","w",stdout);

	int n, i, j, k;
	scanf("%d", &n);

	for (i = n - 1; i >= 1; i--)
	{
		for (k = n; k >= 1; k--)
		{
			for (j = 1; j <= i; j++)
				printf("%d %d\n", k, k + 1);
		}
		for (j = 1; j <= i; j++)
			printf("%d %d\n", n + 1, 1);
	}
	return 0;
}