#include <cassert>
#include<cstdio>

int main ()
{
    int i=0,j=0,k=0,n=0;

    assert(freopen("tije.in","r",stdin));
    assert(freopen("tije.out","w",stdout));

    assert(scanf("%d",&n));
    for(i=1;i<n;i++)
    {
        j=n;
        while (j>0)
        {
            for (k=0; k<i; ++k)
                assert(printf("%d %d\n",j,j+1));
            --j;
        }

        for (j=0; j<i; ++j)
            assert(printf("%d 1\n",n+1));
    }

    return 0;
}