#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> A(n), Ch(100);
  for (int i = 0; i < n; i++) {
    cin >> A[i];
    Ch[A[i] - 1]++;
  }
  int c = 0, d = 0;
  for (int i = 0; i < 100; i++) {
    if (Ch[i] == 1)
      c++;
    else if (Ch[i] > 2)
      d++;
  }
  if (c % 2 == 1 && d == 0)
    cout << "NO" << endl;
  else {
    cout << "YES" << endl;
    int y = c % 2;
    for (int i = 0; i < n; i++) {
      if (Ch[A[i] - 1] == 1) {
        cout << char('A' + c % 2);
        c--;
      } else if (y == 1 && Ch[A[i] - 1] > 2) {
        cout << "A";
        y--;
      } else {
        cout << "B";
      }
    }
  }
}
