package main

import (
	"io"
	"os"
	"strconv"
)

func main() {
	buf, _ := io.ReadAll(os.Stdin)
	pos := 0

	nextInt := func() int {
		for pos < len(buf) && (buf[pos] < '0' || buf[pos] > '9') {
			pos++
		}
		if pos >= len(buf) {
			return 0
		}
		res := 0
		for pos < len(buf) && buf[pos] >= '0' && buf[pos] <= '9' {
			res = res*10 + int(buf[pos]-'0')
			pos++
		}
		return res
	}

	t := nextInt()
	if t == 0 {
		return
	}

	var dp []uint64
	counts := make([]int, 26)
	out := make([]byte, 0, 1024*1024)

	for tc := 0; tc < t; tc++ {
		n := nextInt()
		m := nextInt()
		k := nextInt()

		for i := 0; i < 26; i++ {
			counts[i] = 0
		}

		for i := 0; i < k; {
			if pos >= len(buf) {
				break
			}
			if buf[pos] >= 'A' && buf[pos] <= 'Z' {
				counts[buf[pos]-'A']++
				i++
			}
			pos++
		}

		maxDpLen := (k / 64) + 1
		if cap(dp) < maxDpLen {
			dp = make([]uint64, maxDpLen)
		}

		var ans int64 = 2e18
		computedZero := false

		for X := 0; X < 26; X++ {
			if counts[X] == 0 {
				if computedZero {
					continue
				}
				computedZero = true
			}

			cX := counts[X]
			SRem := k - cX

			dpLen := (SRem / 64) + 1
			dpSlice := dp[:dpLen]
			for i := 0; i < dpLen; i++ {
				dpSlice[i] = 0
			}
			dpSlice[0] = 1

			for i := 0; i < 26; i++ {
				if i == X || counts[i] == 0 {
					continue
				}
				shift := counts[i]
				words := shift / 64
				bits := shift % 64

				for j := dpLen - 1; j >= words; j-- {
					var val uint64
					if bits == 0 {
						val = dpSlice[j-words]
					} else {
						val = dpSlice[j-words] << bits
						if j-words-1 >= 0 {
							val |= dpSlice[j-words-1] >> (64 - bits)
						}
					}
					dpSlice[j] |= val
				}
			}

			minS := n - cX
			if minS < 0 {
				minS = 0
			}
			maxS := k - m
			if maxS > SRem {
				maxS = SRem
			}

			for sum := minS; sum <= maxS; sum++ {
				if (dpSlice[sum/64] & (uint64(1) << (sum % 64))) != 0 {
					nX := n - sum
					if nX < 0 {
						nX = 0
					}
					mX := m - SRem + sum
					if mX < 0 {
						mX = 0
					}
					cost := int64(nX) * int64(mX)
					if cost < ans {
						ans = cost
					}
				}
			}
		}
		out = append(out, strconv.FormatInt(ans, 10)...)
		out = append(out, '\n')
	}
	os.Stdout.Write(out)
}