#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int s[n];
  int f[101] = {};
  for (int i = 0; i < n; i++) {
    cin >> s[i];
    f[s[i]]++;
  }
  int c1 = 0, c2 = 0, c3 = 0;
  for (int i = 1; i <= 100; i++) {
    if (f[i] == 1)
      c1++;
    else if (f[i] == 2)
      c2++;
    else if (f[i] > 2)
      c3++;
  }
  string ch = "A";
  if ((c1 % 2) == 0) {
    cout << "YES\n";
    for (int i = 0; i < n; i++) {
      if (f[s[i]] == 1) {
        cout << ch;
        if (ch == "A")
          ch = "B";
        else
          ch = "A";
      } else
        cout << "A";
    }
  } else if (c3) {
    int z = 0;
    cout << "YES\n";
    for (int i = 0; i < n; i++) {
      if (f[s[i]] == 1) {
        cout << ch;
        if (ch == "A")
          ch = "B";
        else
          ch = "A";
      } else if (f[s[i]] > 2 && z == 0) {
        cout << "B";
        z = 1;
      } else
        cout << "A";
    }
  } else
    cout << "NO";
  return 0;
}
