Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
int main(){
    ll N,A,B,C;cin >> N >> A >> B >> C;
    vector<string> s(N);
    for(int i =0;i <N;i++) cin >> s[i];
    string ansS;
    if (A + B + C == 0) {
        cout << "No" << endl;
        return 0;
    }
    if (A + B + C == 1) {
        rep(i, n) {
            if (s[i] == "AB") {
                if (A == 0 && B == 0) {
                    cout << "No" << endl;
                    return 0;
                }
                if (A == 0) {
                    A = 1; B = 0;
                    ansS += 'A';
                }
                else {
                    A = 0; B = 1;
                    ansS += 'B';
                }
            }
            else if (s[i] == "AC") {
                if (A == 0 && C == 0) {
                    cout << "No" << endl;
                    return 0;
                }if (A == 0) {
                    A = 1; C = 0;
                    ansS += 'A';
                }
                else {
                    A = 0; C = 1;
                    ansS += 'C';
                }
            }
            else {
                if (C == 0 && B == 0) {
                    cout << "No" << endl;
                    return 0;
                }if (C == 0) {
                    C = 1; B = 0;
                    ansS+='C';
                }
                else {
                    C = 0; B = 1;
                    ansS += 'B';
                }
            }
        }
       cout << "Yes" << endl;
       rep(i,N) cout << ansS[i] << endl;
       return 0;
    }
    for(int i = 0; i <N;i++){
        if (s[i] == "AB"){
            if (A == 0 && B == 0) break;
            if (A == 1 && B == 1 && C == 0){
                if (i != N - 1){
                    if (s[i + 1] == "AC"){
                        A++;B--;
                        ansS.push_back('A');
                        continue;
                    }
                    else if (s[i + 1] == "BC") {
                        A--;B++;
                        ansS.push_back('B');
                        continue;
                    }
                }
            }
            if (A >= B){
                A--;B++;
                ansS.push_back('B');
            }
            else{
                A++;B--;
                ansS.push_back('A');
            }
        }
        else if (s[i] == "AC"){
            if (A == 0 && C == 0) break;
            if (A == 1 && B == 0 && C == 1){
                if (i != N-1){
                    if (s[i + 1] == "AB"){
                        A++;C--;
                        ansS.push_back('A');
                        continue;
                    }
                    else if (s[i + 1] == "BC"){
                        A--;C++;
                        ansS.push_back('C');
                        continue;
                    }
                }
            }
            if (A >= C){
                A--;C++;
                ansS.push_back('C');
            }
            else{
                A++;C--;
                ansS.push_back('A');
            }
        }
        else if (s[i] == "BC"){
            if (B == 0 && C == 0) break;
            if (A == 0 && B == 1 && C == 1){
                if (i != N - 1){
                    if (s[i + 1] == "AB"){
                        B++;C--;
                        ansS.push_back('B');
                        continue;
                    }
                    else if (s[i + 1] == "AC"){
                        B--;C++;
                        ansS.push_back('C');
                        continue;
                    }
                }
            }
            if (B >= C){
                B--;C++;
                ansS.push_back('C');
            }
            else{
                B++;C--;
                ansS.push_back('B');
            }
        }
    }
    if (ansS.size() != N) cout << "No" << endl;
    else{
        cout << "Yes" << endl;
        for(int i =0;i <N;i++) cout << ansS[i] << endl;
    }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:16: error: 'n' was not declared in this scope
   15 |         rep(i, n) {
      |                ^
a.cc:4:45: note: in definition of macro 'rep'
    4 | #define rep(i, n) for (int i = 0; i < (int)(n); i++)
      |                                             ^