#include<fstream>
using namespace std;
int i,j,n,k;
int main()
{ifstream q("tije.in");
ofstream w("tije.out");
q>>n;
for(i=n-1;i>=1;i--)
  {for(j=n;j>=1;j--)
     for(k=1;k<=i;k++)
	   w<<j<<" "<<j+1<<"\n";
  }
return 0;}