#include <fstream>
using namespace std;

int N;

void Solve() {

    int i,j,k;
    ofstream out("tije.out");

    for(i=1;i<N;i++){

        for(j=N;j>=1;j--)
            for(k=1;k<=i;k++)
                out<<j<<' '<<j+1<<'\n';

        for(k=1;k<=i;k++)
            out<<N+1<<" 1\n";

        }

    out.close();

}
void Read() {

    ifstream in("tije.in");
    in>>N;
    in.close();

}
int main() {

    Read();
    Solve();

    return 0;

}