#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
constexpr int N = 2e5 + 5;
int t, a, b, p;
string s;
void Solve() {
  cin >> t;
  while (t--) {
    cin >> a >> b >> p >> s;
    s.pop_back();
    vector<ll> suf;
    suf.resize(s.size());
    char last = '0';
    for (int i = s.size() - 1; i >= 0; i--) {
      if (s[i] != last) suf[i] = (s[i] == 'A' ? a : b);
      last = s[i];
    }
    for (int i = suf.size() - 2; i >= 0; i--) suf[i] += suf[i + 1];
    int id = 0;
    while (id < suf.size() && suf[id] > p) id++;
    cout << id + 1 << "\n";
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  Solve();
  return 0;
}
