#include <bits/stdc++.h>

#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define pb push_back

using namespace std;

typedef long long ll;
typedef array<int, 4> ai;
const int maxn = 1e7 + 10;
const int mod = 998244353;

int n;

int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);

	cin >> n;

	if(n & 1){
		rep(i, 0, n){
			rep(j, 0, n){
				int k = ((i - (j - i)) % n + n) % n;
				if(j < k){
					cout << j + 1 << " " << k + 1 << "\n";
				}
			}
		}
	}
	else{
		n--;
		rep(i, 0, n){
			cout << i + 1 << " " << n + 1 << "\n";
			rep(j, 0, n){
				int k = ((i - (j - i)) % n + n) % n;
				if(j < k){
					cout << j + 1 << " " << k + 1 << "\n";
				}
			}
		}
	}

	return 0;
}