#include<bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pf push_front
#define LC k<<1
#define RC k<<1|1
#define IO cin.sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repn(i, a, n) for (int i = a; i <= n; i++)
#define per(i, a, n) for (int i = (n) - 1; i >= a; i--)
#define pern(i, a, n) for (int i = n; i >= a; i--)

typedef long long LL;
typedef long double LD;
typedef unsigned long long ull;
typedef pair<int, int> PII;
typedef pair<int, LL> PIL;
typedef pair<LL, int> PLI;
typedef pair<double, double> PDD;
typedef pair<ull, ull> PUU;
typedef pair<LL, LL> PLL;

const int N = 110;
const int M = 1100000;
const int mod = 1e9+7;
const int inf = (int)1e9;
const LL INF = 1e18;
const double eps = 1e-9;

mt19937_64 Rand((unsigned long long)new char);
#define rand Rand

int n, k;
set<PII> S;
vector<PII> ans;
int f[N][N], a[N], cnt;
void build() {
	rep(i, 1, k) ans.pb(mp(a[i], a[i + 1]));
	repn(i, 1, k) rep(j, 1, k) ans.pb(mp(f[i][j], a[i]));
}
void move() {
	pern(i, 1, k) a[i + 1] = a[i];
	a[1] = a[k + 1];
}
int main() {
	IO;
	cin >> k;
	n = k * k;
	repn(i, 1, k) {
		a[i] = ++cnt;
		rep(j, 1, k) f[i][j] = ++cnt;
	}
	build();
	rep(i, 1, k) {
		repn(j, 1, k) swap(a[j], f[j][i]);
		repn(j, 1, i) move();
		build();
	}
	
	cout << n << "\n";
	for (auto p: ans) {
		// if (p.fi > p.se) swap(p.fi, p.se);
		// assert(!S.count(p));
		// S.insert(p);
		cout << p.fi << " " << p.se << "\n";
	}
	return 0;
}