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