#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")

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

#define el '\n'
#define F first
#define S second

typedef long long ll;
typedef long double ld;

bool multipleTestCases = 0, sublime = 0;
const int N = 1e3 + 5, INF = 1e9 + 5, mod = 1e9 + 7, LOG = 22, SQ = 500;

int n, a[N][3], doneCnt;
bool done[N];
vector<pair<int, int>> ans;
set<pair<int, int>> pos[N];
vector<int> cols[N];
multiset<int> open;

int next() {
    vector<pair<int, int>> v;

    for (int i = 1; i <= n; i++) {
        if (!done[i]) {
            int sum = 0;
            for (auto &j : pos[i]) {
                sum += cols[j.F].size() - 1 - j.S;
            }
            v.push_back({sum, i});
        }
    }

    sort(v.begin(), v.end());

    return v[0].S;
}

int emp() {
    int mn = INF, which = -1;
    for (int i = 1; i <= n + 1; i++) {
        if (cols[i].size() < mn and cols[i].size() < 3) {
            which = i;
        }
    }

    return which;
}

void movee(int from, int to) {
    int col = cols[from].back();

    ans.push_back({from, to});

    pos[col].erase({from, cols[from].size() - 1});
    pos[col].insert({to, cols[to].size()});

    cols[to].push_back(col);
    cols[from].pop_back();

    open.erase(open.find(to));
    open.insert(from);
}

void getRid(int from, int forbid) {
    int col = cols[from].back();

    int to = -1;

    for (int i = 1; i <= n + 1; i++) {
        if (i == forbid or i == from) {
            continue;
        }

        if (cols[i].size() < 3) {
            to = i;
            break;
        }
    }

    movee(from, to);
}

bool cmp(pair<int, int> &a, pair<int, int> &b) {
    int aboveA = cols[a.F].size() - 1 - a.S;
    int aboveB = cols[b.F].size() - 1 - b.S;
    return aboveA < aboveB;
}

void doWork() {
    cin >> n;
    for (int i = 1; i <= n + 1; i++) {
        for (int j = 0; j <= 2; j++) {
            cin >> a[i][j];
            if (a[i][j] == 0) {
                open.insert(i);
                continue;
            }
            pos[a[i][j]].insert({i, j});
            cols[i].push_back(a[i][j]);
        }
    }

    while (doneCnt < n) {
        int tube = emp();
        while (cols[tube].size()) {
            getRid(tube, 0);
        }
        int color = next();

        vector<pair<int, int>> positions;

        for (auto &i : pos[color]) {
            positions.push_back(i);
        }

        sort(positions.begin(), positions.end(), cmp);

        for (auto &p : positions) {
            pair<int, int> now = p;

            int above = cols[now.F].size() - 1 - now.S;

            while (above) {
                getRid(now.F, tube);
                above--;
            }

            movee(now.F, tube);
        }

        done[color] = 1;
        doneCnt++;
    }

    cout << ans.size() << el;

    for (auto &i : ans) {
        cout << i.F << ' ' << i.S << el;
    }
}

signed main() {
#ifdef ONLINE_JUDGE
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
#endif
#ifndef ONLINE_JUDGE
    if (sublime) {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
#endif
    int tests = 1;
    if (multipleTestCases) {
        cin >> tests;
    }
    for (int tc = 1; tc <= tests; tc++) {
        doWork();
    }
}