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