#include <cstdio>

using namespace std;
int i,j,k,n;
int main()
{
    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(i=1; i<=k; i++)
            printf("%d 1\n",n+1);
    }
    return 0;
}