#include <iostream>
#include <fstream>

using namespace std;

ifstream in("lacate.in");
ofstream out("lacate.out");

int n;
int s;
int l = 0;

int main()
{
    in>>n;
    in.close();
    s = ((n-1)*n)/2;
    out<<s<<" "<<s*2<<'\n';
    for(int i=1;i<n;i++)
    {
        for(int j=i+1;j<=n;j++)
            out<<i<<" "<<j<<'\n';
    }
    out.close();
    return 0;
}