#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;

using isize = size_t;
using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;
using i128 = __int128_t;
using u128 = __uint128_t;
using f64 = long double;
using p2 = pair<i64, i64>;
using el = tuple<i64, i64, i64>;
using mint = atcoder::modint998244353;

void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(3);
  _main();
}

i32 pow(i32 x, i32 n) {
  i32 res = 1;
  i32 a = x;
  while (n > 0) {
    if (n & 1) res *= a;
    a *= a;
    n >>= 1;
  }
  return res;
}

void _main() {
  i64 t;
  cin >> t;
  for (;t--;) {
    i64 n;
    string s;
    cin >> n >> s;
    for (i64 i = 0; i < n; i++) {
      if (i % 2 == 0) {
        if (s[i] == 'C') {
          s[i] = 'A';
        } else {
          cout << s << "\n";
          break;
        }
      } else {
        if (s[i] == 'C') {
          cout << s << "\n";
          break;
        } else {
          s[i]++;
        }
      }
    }
  }
}