#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll knapsack(int*c, int n, int m, int k, int last) {
vector<int> dp(n+1,0);
dp[0] = 1;
for (int i = 0; i < 26; i++) {
if (i == last) continue;
for (int j = n-c[i]; j >= 0; j--)
dp[j+c[i]] |= dp[j];
}
ll ans = 1e9;
for (int i = n; i >= n-c[last] && i >= 0; i--) {
if (dp[i]) {
ll a = n-i;
ll b = (i+c[last])-(k-m);
ans = min(ans, a*b);
}
}
return max(0ll,ans);
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
int t;
cin >> t;
while (t--) {
int n, m, k;
cin >> n >> m >> k;
string s;
cin >> s;
int c[26] = {};
for (char ci : s)
c[ci-'A']++;
ll ans = n*m;
for (int i = 0; i < 26; i++) {
ans = min(ans, knapsack(c, n, m, k, i));
}
cout << ans << endl;
}
}