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