#include <iostream>
#include <fstream>
using namespace std;

int n, c=1;

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


int main()
{
    in>>n;
    for(int i=1; i<=n; i++)
        for(int j=1; j<=n; j++)
            if(i!=j && (i%j!=0 || j==1) && (j%i!=0 || i==1)) {
                c++;
                cout<<i<<" "<<j;
            }
    out<<c;
}