#include <algorithm>
#include <iostream>
using namespace std;
bool dp[30000] = {true};
int cnt[26];
void solve()
{
int n, m, k; cin >> n >> m >> k;
string s; cin >> s;
for (int i = 0; i < 26; ++i)
cnt[i] = 0;
for (char c : s)
++cnt[c - 'A'];
int res = m * n;
for (int i = 0; i < 26; ++i)
{
for (int i = 1; i < n; ++i)
dp[i] = false;
for (int j = 0; j < 26; ++j)
if (i != j)
for (int i = n - 1; i >= cnt[j]; --i)
dp[i] |= dp[i - cnt[j]];
for (int j = n - 1; j >= 0; --j)
if (dp[j] && j + cnt[i] >= n)
{
if (j + cnt[i] > k - m)
res = min(res, (n - j) * (m + j + cnt[i] - k));
else
{
cout << "0" << endl;
return;
}
}
}
cout << res << endl;
}
int main()
{
int t; cin >> t;
for (int i = 1; i <= t; ++i)
solve();
return 0;
}