#include <bits/stdc++.h>
using namespace std;
#define N 210000
int n, m, k, ss[N];
bool ok[N];
char S[N];
void doit() {
for (int i = 0; i <= k; i++)
ok[i] = false;
ok[0] = true;
for (int i = 0; i < 26; i++)
for (int j = k; j >= ss[i]; j--)
ok[j] |= ok[j - ss[i]];
}
int main() {
int _;
scanf("%d", &_);
while (_--) {
scanf("%d%d%d", &n, &m, &k);
for (int i = 0; i < 26; i++)
ss[i] = 0;
scanf("%s", S);
for (int i = 0; i < k; i++)
ss[S[i] - 'A']++;
doit();
int ans = 1e9;
for (int i = n; i <= k - m; i++)
if (ok[i])
ans = 0;
for (int i = 0; i < 26; i++) {
int tmp = ss[i];
ss[i] = 0;
doit();
ss[i] = tmp;
for (int j = 0; j <= n; j++)
if (ok[j] && k - ss[i] - j <= m)
ans = min(0LL + ans, 1LL * (n - j) * (m - (k - ss[i] - j)));
}
printf("%d\n", ans);
}
}