#include <fstream>
#include <vector>
#include <cstring>
#include <algorithm>

using namespace std;

ifstream fin("tije.in");
ofstream fout("tije.out");

int main() {

	int n;
	fin >> n;

	for (int step = n - 1; step; --step) {

		for (int i = 1; i <= step; ++i)
			fout << 1 << ' ' << n + 1 << '\n';

		for (int i = 2; i <= n + 1; ++i)
			for (int j = 1; j <= step; ++j)
				fout << i << ' ' << i - 1 << '\n';

	}

	return 0;

}

//Trust me, I'm the Doctor!