Language: C++

#include<bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < n; ++i)
#define rrep(i, n) for(int i = n-1; i >= 0; --i)
#define fi first
#define se second
using namespace std;
using lint = long long;
using uint = unsigned int;
using ulint = unsigned long long;
using ldouble = long double;
using pii = pair<int, int>;
using pli = pair<lint, lint>;
using pdd = pair<double, double>;
using pld = pair<ldouble, ldouble>;
using v1i = vector<int>;
using v1li = vector<lint>;
using v2i = vector<vector<int>>;
using v2li = vector<vector<lint>>;
using v3i = vector<vector<vector<int>>>;
using v3li = vector<vector<vector<lint>>>;
using v1b = vector<bool>;
using v2b = vector<vector<bool>>;
using v3b = vector<vector<vector<bool>>>;
using v1c = vector<char>;
using v2c = vector<vector<char>>;
using v3c = vector<vector<vector<char>>>;
constexpr lint mod1 = 1e9+7;
constexpr lint mod2 = 998244353;

int main(){
  int n, a, b, c; cin >> n >> a >> b >> c; vector<string> s(n+1); rep(i, n) cin >> s[i]; s[n] == "";
  v1c v(n); bool d = 1;
  rep(i, n){
    if(s[i] == "AB"){
      if(a == 0 && b == 0){
        d = 0; break;
      }
      else if(b == 0){
        b++; a--;
        v[i] = 'B';
      }
      else if(a == 0){
        a++ b--;
        v[i] = 'A';
      }
      else{
        if(s[i+1] == "AC"){
          a++ b--;
          v[i] = 'A';
        }
        else{
          b++; a--;
          v[i] = 'B';
        }
      }
    }
    if(s[i] == "AC"){
      if(a == 0 && c == 0){
        d = 0; break;
      }
      else if(c == 0){
        c++; a--;
        v[i] = 'C';
      }
      else if(a == 0){
        a++ c--;
        v[i] = 'A';
      }
      else{
        if(s[i+1] == "AB"){
          a++ c--;
          v[i] = 'A';
        }
        else{
          c++; a--;
          v[i] = 'C';
        }
      }
    }
    if(s[i] == "BC"){
      if(a == 0 && b == 0){
        d = 0; break;
      }
      else if(b == 0){
        b++; c--;
        v[i] = 'B';
      }
      else if(c == 0){
        c++ b--;
        v[i] = 'C';
      }
      else{
        if(s[i+1] == "AC"){
          c++ b--;
          v[i] = 'C';
        }
        else{
          b++; c--;
          v[i] = 'B';
        }
      }
    }
  }
  if(d){
    cout << "Yes" << "\n";
    rep(i, n){
      cout << v[i] << "\n";
    }
  }
  else cout << "No" << "\n";
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:31:95: warning: ignoring return value of 'bool std::operator==(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*) [with _CharT = char; _Traits = char_traits<char>; _Alloc = allocator<char>]', declared with attribute 'nodiscard' [-Wunused-result]
   31 |   int n, a, b, c; cin >> n >> a >> b >> c; vector<string> s(n+1); rep(i, n) cin >> s[i]; s[n] == "";
In file included from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/bits/basic_string.h:3772:5: note: declared here
 3772 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
a.cc:43:12: error: expected ';' before 'b'
   43 |         a++ b--;
      |            ^~
      |            ;
a.cc:48:14: error: expected ';' before 'b'
   48 |           a++ b--;
      |              ^~
      |              ;
a.cc:66:12: error: expected ';' before 'c'
   66 |         a++ c--;
      |            ^~
      |            ;
a.cc:71:14: error: expected ';' before 'c'
   71 |           a++ c--;
      |              ^~
      |              ;
a.cc:89:12: error: expected ';' before 'b'
   89 |         c++ b--;
      |            ^~
      |            ;
a.cc:94:14: error: expected ';' before 'b'
   94 |           c++ b--;
      |              ^~
      |              ;