#include <fstream>

using namespace std;
int i,j,k,n;
int main()
{
    ifstream f("tije.in");
    ofstream g("tije.out");
    f>>n;
    for(k=n-1; k>=1; k--)
    {
        for(i=n; i>=1; i--)
        for(j=1; j<=k; j++)
            g<<i<<" "<<i+1<<'\n';
        for(i=1; i<=k; i++)
            g<<n+1<<" 1\n";
    }
    return 0;
}