#include <iostream>
#include <fstream>
using namespace std;


ifstream fin("tije.in");
ofstream fout("tije.out");
int N;
void read(), write();
void make(int &i)
{
	++i;
	if (i == N + 1) i = 1;
}

int main()
{
	read(), write();
	return 0;
}

void read()
{
	fin >> N;
	fin.close();
}

void write()
{
	for (int foo = 1; foo < N; ++foo)
	{
		for (int i = N; i >= 1; --i)
		{
			fout << i << ' ' << N + 1 << '\n';
		}
	}
	for (int i = 2; i != 1; make(i))
	{
		for (int foo = 1, k = i; foo <= N; ++foo, make(k))
		{
			fout << N + 1 << ' ' << k << '\n';
		}
	}
	fout.close();
}