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

using ll = long long;
using VI = vector<int>;
using P = pair<int, int>;

#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define FOR(i, a, b) for (ll i = a; i < (ll)(b); i++)
#define ALL(a) (a).begin(),(a).end()

constexpr int INF = 1001001001;
constexpr ll LINF = 1001001001001001001ll;
constexpr int DX[] = {1, 0, -1, 0};
constexpr int DY[] = {0, 1, 0, -1};

template< typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true); }
template< typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true); }

const ll MOD = 1000000007;

int main() {
    int N;
    cin >> N;
    cout << 2 * N - 1 << endl;
    REP(i, 2 * N - 1) {
        REP(j, N) {
            if (j < N - 1) {
                if (i + j > 2 * N - 2) cout << j + 1 << " ";
                else cout << 2 * N - 1 - j << " ";
            } else {
                if (i < N) cout << i + 1 << endl;
                else cout << N << endl;
            }
        }
    }
}