#include <iostream>
#include <vector>
#include <algorithm>
#include <set>

using namespace std;

void solve()
{
  int n;
  cin >> n;
  string s;
  cin >> s;
  int flag = 0;
  for (int i = 0; i < n; ++i)
  {
    if (i % 2 == 0)
    {
      if (flag || s[i] != 'C')
      {
        cout << s << endl;
        return;
      }
      else
      {
        s[i] = 'A';
      }
    }
    else
    {
      if (s[i] == 'C')
      {
        cout << s << endl;
        return;
      }
      else
      {
        if (s[i] == 'A') flag = 1;
        ++s[i];
      }
    }
  }
  cout << s << endl;
}

int main()
{
  int t;
  cin >> t;
  while (t--) solve();
}