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