#include<bits/stdc++.h>
using namespace std;
const int maxn = 2*1e5+5;
int t;
int n,m,k;
char s[maxn];
int a[30];
int dp[maxn];
int main()
{
	scanf("%d",&t);
	while(t--)
	{
		scanf("%d%d%d", &n, &m, &k);
		scanf("%s", s);
		for (int i = 0; i < 26; i++)
			a[i] = 0;
		for (int i = 0; i < k; i++)
			a[(int)(s[i] - 'A')]++;
		int ans = n * m;
		for (int p = 0; p < 26; p++) {
			for (int i = 0; i <= k; i++)
				dp[i] = 0;
			dp[0] = 1;
			for (int i = 0; i < 26; i++) {
				if (i == p) continue;
				for (int j = k; j >= a[i]; j--)
				{
					if(dp[j-a[i]])
						dp[j]=1;
				}
			}
			for (int i = 0; i <= k; i++) {
				if (!dp[i]) continue;
				int x = max(0, n - i);
				int y = max(0, m - (k - a[p] - i));
				if (x + y > a[p]) continue;
				ans = min(ans, x * y);
			}
		}
		printf("%d\n",ans);
	}
	return 0;
}