#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using unit = unsigned;
using vl = vector<ll>;
using ull = unsigned long long;
using vvi = vector<vi>;
using pii = pair<int, int>;
using vvl = vector<vl>;
using pll = pair<ll, ll>;
using vp = vector<pii>;
void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  _main();
}
template <class T>
string join(const vector<T> &v) {
  stringstream s;
  for (int i = (int)(0); i < (int)(((long long)(v).size())); ++i)
    s << ' ' << v[i];
  return s.str().substr(1);
}
template <class T>
istream &operator>>(istream &i, vector<T> &v) {
  for (auto &x : v) {
    i >> v;
  }
  return i;
}
template <class T>
ostream &operator<<(ostream &o, const vector<T> &v) {
  o << "[";
  for (auto &x : v) o << x << ",";
  o << "]";
  return o;
}
template <class T>
ostream &operator<<(ostream &o, const deque<T> &v) {
  o << "deq[";
  for (auto &x : v) o << x << ",";
  o << "]";
  return o;
}
template <class T>
ostream &operator<<(ostream &o, const set<T> &v) {
  o << "{";
  for (auto &x : v) o << x << ",";
  o << "}";
  return o;
}
template <class T>
ostream &operator<<(ostream &o, const unordered_set<T> &v) {
  o << "{";
  for (auto &x : v) o << x << ",";
  o << "}";
  return o;
}
template <class T>
ostream &operator<<(ostream &o, const multiset<T> &v) {
  o << "{";
  for (auto &x : v) o << x << ",";
  o << "}";
  return o;
}
template <class T>
ostream &operator<<(ostream &o, const unordered_multiset<T> &v) {
  o << "{";
  for (auto &x : v) o << x << ",";
  o << "}";
  return o;
}
template <class T1, class T2>
ostream &operator<<(ostream &o, const pair<T1, T2> &p) {
  o << "(" << p.first << "," << p.second << ")";
  return o;
}
template <class TK, class TV>
ostream &operator<<(ostream &o, const map<TK, TV> &m) {
  o << "{";
  for (auto &x : m) o << x.first << "=>" << x.second << ",";
  o << "}";
  return o;
}
template <class TK, class TV>
ostream &operator<<(ostream &o, const unordered_map<TK, TV> &m) {
  o << "{";
  for (auto &x : m) o << x.first << "=>" << x.second << ",";
  o << "}";
  return o;
}
template <class T>
void YES(T c) {
  if (c)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
template <class T>
void Yes(T c) {
  if (c)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
template <class T>
void POSS(T c) {
  if (c)
    cout << "POSSIBLE" << endl;
  else
    cout << "IMPOSSIBLE" << endl;
}
template <class T>
void Poss(T c) {
  if (c)
    cout << "Possible" << endl;
  else
    cout << "Impossible" << endl;
}
template <class T>
void chmax(T &a, const T &b) {
  if (a < b) a = b;
}
template <class T>
void chmin(T &a, const T &b) {
  if (b < a) a = b;
}
template <class T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF = 1001002003;
const ll LINF = 1001002003004005006LL;
const int dx[] = {-1, 0, 1, 0, -1, -1, 1, 1};
const int dy[] = {0, 1, 0, -1, -1, 1, -1, 1};
int solve() {
  int a, b, p;
  string s;
  cin >> a >> b >> p >> s;
  reverse((s).begin(), (s).end());
  int n = ((long long)(s).size());
  map<char, int> m{
      {'A', a},
      {'B', b},
  };
  int i = 1;
  char now = s[1];
  p -= m[now];
  if (p < 0) return n;
  while (i < n) {
    if (i + 1 < n && s[i + 1] == now) {
      ++i;
      continue;
    }
    now = s[i + 1];
    p -= m[now];
    if (p < 0) return n - i;
    ++i;
  }
  return 1;
}
void _main() {
  int t;
  cin >> t;
  vi a(t);
  for (int i = (int)(0); i < (int)(t); ++i) a[i] = solve();
  for (int i = (int)(0); i < (int)(t); ++i) cout << a[i] << endl;
}
