///Enta etfsh5t nseet el rank

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")

#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update

using namespace std;
using namespace __gnu_pbds;

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,
        tree_order_statistics_node_update>;
#define pb push_back
#define F first
#define S second
#define f(i, a, b) for (int i = a; i < b; i++)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define sz(x) (int)(x).size()
//#define mp(x, y) make_pair(x, y)
#define popCnt(x) (__builtin_popcountll(x))
#define int ll

using ll = long long;
using ull = unsigned long long;
using uint = uint32_t;
using ii = pair<int, int>;

const int N = 1e3 + 20, LG = 18, MOD = (119 << 23) + 1;
const long double PI = acos(-1);

const long double EPS = 1e-9;

vector<int> zeros;
vector<int> vec[N];
vector<ii> moves;

void move(int x, int y) {
    moves.push_back({x + 1, y + 1});
    int ptr1 = 2, ptr2 = 0;
    while (vec[x][ptr1] == 0) {
        ptr1 -= 1;
    }
    while (vec[y][ptr2])
        ptr2 += 1;
    swap(vec[x][ptr1], vec[y][ptr2]);
    for (auto &v: zeros) {
        if (v == y) {
            v = x;
            break;
        }
    }
}

void swap(int x, int pos_x, int y, int pos_y) {
    if (pos_y == 1 && pos_x == 0) {
        int pivot = (y + 1) + (x == (y + 1));
        while (!vec[pivot][1])
            move(x, pivot);
        swap(x, pos_x, pivot, 2);
        swap(pivot, 2, y, pos_y);
        return;
    }
    while (vec[y][pos_y]) {
        for (auto v: zeros) {
            if (v != x && v != y) {
                move(y, v);
                break;
            }
        }
    }
    while (pos_x < 2 && vec[x][pos_x + 1]) {
        for (auto v: zeros) {
            if (v != x && v != y) {
                move(x, v);
                break;
            }
        }
    }
    move(x, y);

}

void doWork() {
    int n;
    cin >> n;
    f(i, 0, n + 1) {
        vec[i].resize(3);
        f(j, 0, 3) {
            cin >> vec[i][j];
            if (!vec[i][j])
                zeros.push_back(i);
        }
    }
    for (int i = 0; i < n; i++) {
        if (!vec[i][0])move(i + 1, i);
        int targetColour = vec[i][0];
        for (int j = 1; j < 3; j++)
            if (vec[i][j] != targetColour) {
                bool ok = false;
                for (int k = 2; k >= 0 && !ok; --k)
                    f(x, i + 1, n + 1)
                        if (vec[x][k] == targetColour) {
                            swap(x, k, i, j);
                            ok = true;
                            break;
                        }
            }
    }
    cout << moves.size() << '\n';
    for (auto p: moves)
        cout << p.F << ' ' << p.S << '\n';

}

int32_t main() {
#ifdef ONLINE_JUDGE
    ios_base::sync_with_stdio(0);
    cin.tie(0);
#endif // ONLINE_JUDGE
    int t = 1;
//    cin >> t;
    while (t--)
        doWork();
    return 0;
}