#include<stdio.h>
FILE*f=fopen("tije.in","r");
FILE*g=fopen("tije.out","w");
long i,j,n,k,x;
int main(void)
{
fscanf(f,"%ld",&n);
for(i=n-1;i>=1;i--)
{
	for(j=n;j>=1;j--)
		{
		for(k=1;k<=i;k++)
		 {
		 fprintf(g,"%ld %ld\n",j,j+1);
		 }
		}
	for(k=1;k<=i;k++)
	{
	fprintf(g,"%ld 1\n",n+1);
	}
}
return 0;
}