#include <fstream>

using namespace std;
ifstream fin("submultimi.in");
ofstream fout("submultimi.out");
int i,n,sol,sub;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)fout<<i<<"\n";
    for(i=1;i<=n;i++)
        {
            if((i+1)<=n)fout<<i<<" "<<i+1<<"\n";
                else fout<<i<<" "<<i-(n-1)<<"\n ";
        }
    return 0;
}