#include <iostream>
#include <vector>
#include <random>
#include <algorithm>
#include <cassert>
using namespace std;

const int mn = 1002;
vector<int> board[mn];
vector<int> pos[mn];
int n;

vector<pair<int, int>> moves;
void move(int a, int b) {
	//cout << "move " << a << ' ' << b << endl;
	int x = board[a].back();
	if (pos[x][0] == a) pos[x][0] = b;
	else if (pos[x][1] == a) pos[x][1] = b;
	else if (pos[x][2] == a) pos[x][2] = b;
	board[b].push_back(board[a].back());
	board[a].pop_back();
	/*for (int i = 1; i <= n+1; i++) {
		for (int j : board[i]) cout << j << ' ';
		cout << endl;
	}
	cout << endl;*/
	moves.push_back({a, b});
}

void bring(int &color, int &j, int &last) {
	int blank = 1;
	while (blank == j || blank == last) blank++;
	if (board[j][2] == color) {
		return;
	}
	if (board[j][0] == color) {
		//cout << "bring bot" << endl;
		move(j, last);
		move(j, last);
		move(j, last);
		swap(last, j);
		return;
	}
	if (board[j][1] == color) {
		move(blank, last);
		move(j, blank);
		move(j, last);
		move(blank, j);
		move(last, j);
		move(last, blank);
	}
}

int main() {
	cin >> n;
	for (int i = 1; i <= n+1; i++) {
		for (int j = 0; j < 3; j++) {
			int x; cin >> x;
			if (x) {
				board[i].push_back(x);
				pos[x].push_back(i);
			}
		}
	}
	int last = 1;
	for (int i = 2; i <= n+1; i++) {

		while (board[last].size() < 3) {
			move(i, last);
		}
		if (board[last].size() == 3) last = i;
	}
	vector<int> ordering(n);
	for (int i = 0; i < n; i++) ordering[i] = i+1;
	mt19937 rng;
	shuffle(ordering.begin(), ordering.end(), rng);

	for (int i : ordering) {
		//cout << "choose " << i << endl;
		if (pos[i][0] == pos[i][1] && pos[i][1] == pos[i][2]) continue;
		else {
			if (pos[i][0] == pos[i][2]) swap(pos[i][2], pos[i][1]);
			if (pos[i][1] == pos[i][2]) {
				swap(pos[i][0], pos[i][2]);
			}
			int x = pos[i][0], y = pos[i][1], z = pos[i][2];
			int blank = 1;
			if (x != y) {
				bring(i, x, last);
				bring(i, y, last);
				bring(i, z, last);
				move(x, last);
				move(y, last);
				move(z, last);
				move(z, y);
				move(z, x);
				last = z;
			}
			else {
				int x = pos[i][0], y = pos[i][2];
				bring(i, x, last);
				bring(i, y, last);
				move(x, last);
				move(y, last);
				assert(board[x].size() == 2);
				if (board[x][1] == i) {
					move(x, last);
					move(x, y);
					last = x;
				}
				else {
					move(x, y);
					move(x, last);
					last = x;
				}
			}
		}
	}
	/*for (int i = 1; i <= n+1; i++) {
		for (int j : board[i]) cout << j << ' ';
		cout << endl;
	}*/
	for (int i = 1; i <= n+1; i++) {
		if (board[i].size()) 
			for (int j = 0; j < board[i].size(); i++) assert(board[i][j] == board[i][0]);
	}
	cout << moves.size() << endl;
	for (auto [a, b] : moves) cout << a << ' ' << b << endl;
}