#include <algorithm>
#include <cassert>
#include <queue>
#include <vector>
#include <iostream>
using namespace std;
int main() {
    int n; cin >> n;

    vector<int> adj[n+1];
    vector<int> leaves;
    for (int i = 1; i <= n; i++) {
        if (2 * i <= n) {
            adj[i].push_back(2 * i);
            adj[i].push_back(2 * i + 1 <= n ? 2 * i + 1 : 1);
        } else {
            leaves.push_back(i);
        }
    }

    assert(leaves.size() * 2 >= n);

    int i = 1;
    for (int k : leaves) {
        adj[k].push_back((i > n) ? 1 : i);
        i++;
        adj[k].push_back((i > n) ? 1 : i);
        i++;
    }

    assert(i >= n);

    for (int i = 1; i <= n; i++)
        cout << adj[i][0] << ' ' << adj[i][1] << endl;

    // check
    // for (int i = 1; i <= n; i++) {
    //     vector<int> dist(n+1, 1<<30);
    //     queue<int> q;
    //     q.push(i);
    //     dist[i] = 0;
    //     while (!q.empty()) {
    //         int v = q.front(); q.pop();
    //         for (int u : adj[v])
    //             if (dist[u] == 1<<30) {
    //                 dist[u] = dist[v] + 1;
    //                 q.push(u);
    //             }
    //     }
    //     // for (auto x : dist) cerr << x << ' '; cerr << endl;
    //     assert(*max_element(dist.begin()+1, dist.end()) <= 10);
    // }
}

#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

int n;
int main() {
	scanf("%d",&n);
	rep(i,0,n) printf("%d %d\n",(i*2)%n+1,(i*2+1)%n+1);
}
