#include <iostream>
#include <cmath>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <array>
#include <iterator>
#include <algorithm>
// #include <bit>
#include <numeric>
#include <iomanip>
#include <bitset>
using namespace std;
// #pragma GCC optimize ("Ofast")
// #pragma GCC target ("avx2")
#define el << '\n'
#define nl cout << '\n'
#define cina(a,n) for (int i=0; i<n; i++) cin >> a[i]
#define ll long long
#define spc << ' '
#define forn(i,n) for (int i=0; i<n; i++)
#define forl(i,s,e) for (int i=s; i<e; i++)
#define pb push_back
#define ansyes cout << "YES\n"
#define ansno cout << "NO\n"
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pss pair<short, short>
#define MAX *max_element
#define MIN *min_element
#define rsz resize
#define sz(x) ((int) x.size())
#define all(x) x.begin(), x.end()
#define bsi(x, v) (int) (lower_bound(x.begin(), x.end(), v) - x.begin());
const int inf = 1000000000;
const ll inf2 = 4000000000000000000;
    
int main() {
    // ios_base::sync_with_stdio(false);
    // cin.tie(NULL);
    int n; cin >> n;
    if (n%2) {
        forn(i,n) {
            forn(j,n/2) {
                cout << (i+n-j)%n+1 spc << (i+j+1)%n+1 el;
            }
        }
    }
    else {
        forn(i,n-1) {
            forn(j,n/2-1) {
                cout << (i+n-1-j)%(n-1)+1 spc << (i+j+1)%(n-1)+1 el;
            }
            cout << (i+n/2)%(n-1)+1 spc << n el;
        }
    }
    cout.flush();
}