#include <stdio.h>

FILE *f,*s;

int n,i,j,k;

int main()
{
	f=fopen("tije.in","r");
	s=fopen("tije.out","w");

	fscanf(f,"%d",&n);
	
	for(i=n-1;i>=1;i--)
	{
		for(j=n;j>=1;j--)
		{
			for(k=1;k<=i;k++)
				fprintf(s,"%d %d\n",j,j+1);
		}
		
		for(k=1;k<=i;k++)
			fprintf(s,"%d %d\n",n+1,1);
		
	}
	
	fclose(s);
	
	return 0;
}