#include <bits/stdc++.h>
using namespace std;
bool is_prime(long long n) {
  for (long long i = 2; i * i <= n; ++i) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}
vector<long long> fact(long long n) {
  vector<long long> ans;
  for (int i = 2; i * i <= n; i++) {
    if (n % i == 0) {
      long long ct = 0;
      while (n % i == 0) {
        ct++;
        n /= i;
        ans.push_back(i);
      }
    }
  }
  if (n > 1) {
    ans.push_back(n);
  }
  return ans;
}
inline long long getPow(long long a, long long b) {
  long long res = 1ll, tp = a;
  while (b) {
    if (b & 1ll) {
      res *= tp;
    }
    tp *= tp;
    b >>= 1ll;
  }
  return res;
}
long long vec_mult(long long x1, long long y1, long long x2, long long y2,
                   long long x3, long long y3) {
  return abs((x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1));
}
void ok() {
  cout << "YES" << endl;
  exit(0);
}
void no() {
  cout << "NO" << endl;
  exit(0);
}
inline long long nxt() {
  long long x;
  cin >> x;
  return x;
}
const long long N = 2e5 + 5, inf = 9e18;
int days[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);
  long long t = nxt();
  while (t--) {
    long long n = nxt(), m = nxt(), k = nxt();
    string s;
    cin >> s;
    vector<long long> ct(26);
    for (int i = 0; i < k; i++) {
      ct[s[i] - 'A']++;
    }
    long long ans = n * m;
    for (int p = 0; p < 26; p++) {
      if (!ct[p]) continue;
      vector<long long> dp(k + 1, 0LL);
      dp[0] = 1;
      for (int i = 0; i < 26; i++) {
        if (i == p) continue;
        for (int j = k; j >= ct[i]; j--) {
          dp[j] |= dp[j - ct[i]];
        }
      }
      for (int i = 0; i <= k; i++) {
        if (!dp[i]) continue;
        long long x = max(n - i, 0LL);
        long long y = max(m - (k - ct[p] - i), 0LL);
        if (x + y > ct[p]) continue;
        ans = min(ans, x * y);
      }
    }
    cout << ans << endl;
  }
  return 0;
}
