Language: C++

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
using P = pair<int,int>;
/* ちゃんと考えてわかって実装 */


int main(void){
    int N;
    map<char, ll> abc;
    cin >> N;
    cin >> abc['A'] >> abc['B'] >> abc['C'];

    vector<string> s;
    for(int i=0; i<N; i++){
        string tmp_s;
        cin >> tmp_s;
        s.push_back(tmp_s);
    }

    if(A+B+C == 0) cout << "No" << endl;
    else if(A+B+C == 1){
        vector<char> ans1;
        for(int i=0; i<N; i++){
            if(abc[s[i][0]] == 0 && abc[s[i][1]] == 0){
                cout << "No" << endl;
                break;
            }
            else{
                if(abc[s[i][0]] == 1){
                    ans1.push_back(s[i][1]);
                    abc[s[i][1]]++;
                    abc[s[i][0]]--;
                }
                else{
                    ans1.push_back(abc[s[i][0]]);
                    abc[s[i][0]]++;
                    abc[s[i][1]]--;
                }

            }
        }
        if(ans1.size() == N){
            cout << "Yes" << endl;
            for(int i=0; i<N; i++){
                cout << ans1[i] << endl;
            }
        }
    }
    else{
        if(abc[s[0][0]] + abc[s[0][1]] == 0) cout << "No" << endl;
        else{
            cout << "Yes" << endl;
            for(int i=0; i<N; i++){
                if(abc[s[i][0]] < abc[s[i][1]]){
                    abc[s[i][0]]++;
                    abc[s[i][1]]--;
                    cout << s[i][0] << endl;
                }
                else if(abc[s[i][0]] == 1 && abc[s[i][1]] == 1 && 
                        abc['A'] + abc['B'] + abc['C'] == 2){
                            if(i != N-1 && s[i] != s[i+1]){
                                if(s[i][0] == s[i+1][0]){
                                    abc[s[i][0]]++;
                                    abc[s[i][1]]--;
                                    cout << s[i][0] << endl;
                                }
                                else if(s[i][0] == s[i+1][1]){
                                    abc[s[i][0]]++;
                                    abc[s[i][1]]--;
                                    cout << s[i][0] << endl;
                                }
                                else if(s[i][1] == s[i+1][0]){
                                    abc[s[i][0]]--;
                                    abc[s[i][1]]++;
                                    cout << s[i][1] << endl;
                                }
                                else if(s[i][1] == s[i+1][1]){
                                    abc[s[i][0]]--;
                                    abc[s[i][1]]++;
                                    cout << s[i][1] << endl;

                                }
                            }
                            else{
                                abc[s[i][0]]++;
                                abc[s[i][1]]--;
                                cout << s[i][0] << endl;
                            }
                        }
                else{
                    abc[s[i][0]]--;
                    abc[s[i][1]]++;
                    cout << s[i][1] << endl;
                }
            }
        }
    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:21:8: error: 'A' was not declared in this scope
   21 |     if(A+B+C == 0) cout << "No" << endl;
      |        ^
a.cc:21:10: error: 'B' was not declared in this scope
   21 |     if(A+B+C == 0) cout << "No" << endl;
      |          ^
a.cc:21:12: error: 'C' was not declared in this scope
   21 |     if(A+B+C == 0) cout << "No" << endl;
      |            ^