#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

using mint = modint998244353;

void debug_mint1(vector<mint> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        cerr << vec[i].val() << " ";
    }
    cerr << endl;
}

void debug_mint2(vector<vector<mint>> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        for (int j = 0; j < vec[i].size(); j++) {
            cerr << vec[i][j].val() << " ";
        }
        cerr << endl;
    }
}

int main() {
    string player;
    cin >> player;
    ll N;
    cin >> N;
    cout << N - 2 << endl;
    if (player == "Alice"){
        vector<ll> U(N - 1);
        vector<ll> V(N - 1);
        rep(i, N - 1){
            cin >> U[i] >> V[i];
            U[i]--;
            V[i]--;
        }
        vector<ll> ans;
        vector<vector<bool>> graph(N, vector<bool>(N, false));
        vector<ll> degs(N, 0);
        for (ll i = 0; i < N - 1; i++){
            graph[U[i]][V[i]] = true;
            graph[V[i]][U[i]] = true;
            degs[U[i]]++;
            degs[V[i]]++;
        }
        rep(i, N - 2){
            ll min_id = N + 1;
            rep(j, N){
                if (degs[j] == 1){
                    min_id = j;
                    break;
                }
            }
            for (ll j = 0; j < N; j++){
                if (graph[min_id][j]){
                    graph[min_id][j] = false;
                    graph[j][min_id] = false;
                    ans.push_back(j + 1);
                    degs[min_id]--;
                    degs[j]--;
                    break;
                }
            }
        }
        for (ll j = 0; j < N - 2; j++){
            cout << ans[j] + 1;
            if (j < N - 3) cout << " ";
        }
        cout << endl;
    }
    else{
        vector<ll> pf(N - 2);
        rep(i, N - 2) cin >> pf[i];
        vector<ll> aps(N, 1);
        rep(i, N - 2){
            aps[pf[i] - 1]++;
        }
        vector<ll> U;
        vector<ll> V;
        for (ll i = 0; i < N - 2; i++){
            for (ll j = 0; j < N; j++){
                if (aps[j] == 1){
                    U.push_back(j + 1);
                    V.push_back(pf[i] + 1);
                    aps[pf[i]]--;
                    aps[j]--;
                }
            }
        }
        rep(i, N){
            if (aps[i] == 1){
                if (U.size() == N - 2) U.push_back(i + 1);
                else V.push_back(i + 1);
            }
        }
        rep(i, N - 1){
            cout << U[i] << " " << V[i] << endl;
        }
    }
}