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