#include <iostream>
#include <fstream>

using namespace std;

int main(int argc, char *argv[]) {
	int n(0);

	ifstream fin("tije.in");
	fin >> n;
	fin.close();

	ofstream fout("tije.out");
	for (int i = n - 1; i > 0; --i) {
		for (int j = n; j >= 1; --j) {
			int s = j;
			int d = j + 1;
			for (int k(0); k < i; ++k)
				fout << s << " " << d << endl;
		}
		for (int k(0); k < i; ++k)
			fout << n + 1 << " " << 1 << endl;
	}
	fout.close();

	return 0;
}