#include <cstdio>
int main()
{
    freopen("tije.in","rt",stdin);
    freopen("tije.out","wt",stdout);

	int N;
    scanf("%d",&N);
	int step,i,j;

	step=N-1;
	while( step )
	{
		i=N;
		while( i )
		{
			j=step;
			while( j )
			{
			printf("%d %d\n",i,i+1);
			--j;
			}
			--i;
		}

		i=step;
		while( i-- )
			printf("%d %d\n",N+1,1);
		--step;
	}
	return 0;
}//while() vs for()