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

#define int long long
#define double long double

#define pii pair<int, int>

array<vector<int>, 3> v, b;
vector<int> p(20), q(20);
vector<pii> r;

void solve(int n, int i = -1, bool z = true) {
	if (n == 0) {
		return;
	}
	if (z) {
		i = q[n];
	}
	//cout << "task: move " << n << " to " << i+1 << endl;
	if (p[n] == i) {
		solve(n - 1, i, z);
		return;
	}
	for (int j = 0; j < 3; j++) {
		if (p[n] != j && i != j) {
			solve(n - 1, j, false);
			break;
		}
	}
	r.emplace_back(p[n], i);
	p[n] = i;
	solve(n - 1, i, z);
}

void printPattern() {
    cout << "6" << endl;
    cout << "1 3" << endl;
    cout << "1 2" << endl;
    cout << "3 1" << endl;
    cout << "3 2" << endl;
    cout << "1 2" << endl;
    cout << "1 3" << endl;
}

signed main() {
    printPattern();
    return 0;
}