#include <fstream>

using namespace std;

ifstream fin("tije.in");
ofstream fout("tije.out");

int N, i;
int j, cnt;

int main()
{
    fin >> N;
    for (i=N-1; i>=1; i--)
    {
        for (j=N; j>=1; j--)
          for (cnt=1; cnt<=i; cnt++)
            fout << j << " " << j+1 << '\n';
        for (j=1; j<=i; j++)
          fout << N+1 << " " << 1 << '\n';
    }
    fin.close();
    fout.close();
    return 0;
}