using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
public class Solution {
    static void Main(String[] args) {
        int t = Convert.ToInt32(Console.ReadLine());
        for(int a0 = 0; a0 < t; a0++){
            string[] tokens_n = Console.ReadLine().Split(' ');
            int n = Convert.ToInt32(tokens_n[0]);
            int k = Convert.ToInt32(tokens_n[1]);
            string num = Console.ReadLine();
            Console.WriteLine(StringToList(num,n,k));
        }
    }
 
    static long StringToList(string n, int len , int subLen)
    {
        long max=long.MinValue;
        for(var i=0; i<len-subLen; i++)
        {
           long p = ProdcutOfDigit(n.Substring(i,subLen));
           if(p>max)
           {
               max =p;
           }
        }
        return max;
    }
 
    static long ProdcutOfDigit(string n)
    {
        long m =1;
        var arr = n.ToCharArray().ToList().Select(s=>Convert.ToInt64(s.ToString())).ToList();
        foreach(var i in arr)
        {
            m*=i;
        }
        return m;
    }
}

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