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

#ifdef _RUTHEN
#include "debug.hpp"
#else
#define show(...) true
#endif

using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)
template <class T> using V = vector<T>;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T;
    cin >> T;
    while (T--) {
        int N;
        cin >> N;
        string S;
        cin >> S;
        V<char> stk;
        for (int i = N - 1; i >= 0; i--) {
            stk.push_back(S[i]);
            int len = stk.size();
            if (len >= 2 && stk[len - 1] == 'A' && stk[len - 2] == 'B') {
                if (len == 2) {
                    continue;
                } else if (stk[len - 3] == 'B') {
                    stk.pop_back();
                    stk.pop_back();
                } else if (len == 3) {
                    continue;
                } else if (stk[len - 4] == 'A') {
                    continue;
                } else {
                    continue;
                }
            }
        }
        string ans;
        for (auto &c : stk) ans += c;
        reverse(ans.begin(), ans.end());
        cout << ans << '\n';
    }
    return 0;
}