// Source: https://usaco.guide/general/io

#include <bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin >> n;
	if(n%2 == 0){
		n--;
	}
	for(int i = 0;i < n;i++){
		for(int j = 0;j < n/2;j++){
			int a = (i-j+n)%n;
			int b = (i+j+1)%n;
			if(a > b){
				swap(a,b);
			}
			cout << a+1 << " " << b+1 << endl;
		}
		if(n%2==1){
			cout << (i+n/2+1)%n+1 << " " << n+1 << endl;
		}
	}
}