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

#define rep(i, n) for(int i = 0; i < n ; i++)
#define rep2(i, a, b) for(int i = a; i <= b ; i++)
int main(){
    int n;
    cin >> n;
    int G[n][n] = {};
    vector<pair<int, int>> ans;
    int m = n-1;
    rep(i, n){
        int cur = m;
        int cnt = 0;
        rep(j, n) if(G[i][j]) cnt++;
        if(cur - cnt <= 0 && cnt >= 1){
            m = cnt-1;
            continue;
        }
        rep2(j, i+1, n-1){
            if(cur){
                G[i][j] = 1;
                ans.push_back({i+1, j+1});
                cur--;
            }
            else break;
        }
        m--;
    }
    rep(i, (int)ans.size()) cout << ans[i].first << " "  << ans[i].second << endl;
}