#include <iostream>
#include <fstream>
#include <cstring>
#include <stdio.h>

using namespace std;

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

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

	char res[32];

	FILE *fout = fopen("tije.out", "w");
	for (int i = n - 1; i > 0; --i) {
		for (int j = n; j >= 1; --j) {
			int s = j;
			int d = j + 1;

			sprintf(res, "%d %d", s, d);

			for (int k(0); k < i; ++k)
				fprintf(fout, "%s\n", res);
		}
		sprintf(res, "%d 1", n + 1);
		for (int k(0); k < i; ++k)
			fprintf(fout, "%s\n", res);
	}
	fclose(fout);

	return 0;
}