import Control.Applicative
import Control.Monad
import System.IO
import Data.Char(digitToInt)

slice :: Int -> Int -> [a] -> [a]
slice start end xs = take (end - start) (drop start xs)

strMult :: [Char] -> Int
strMult [chr] = digitToInt chr
strMult (chr:str) = (digitToInt chr) * (strMult str)  

subMult :: [Char] -> Int -> Int -> [Int]
subMult num start end 
    | end == (length num) - 1 = [strMult (slice start end num)]
    | otherwise = (strMult (slice start end num)):(subMult num (start+1) (end+1))

main :: IO ()
main = do
    t_temp <- getLine
    let t = read t_temp :: Int
    forM_ [1..t] $ \a0  -> do
        n_temp <- getLine
        let n_t = words n_temp
        let n = read $ n_t!!0 :: Int
        let k = read $ n_t!!1 :: Int
'
        num <- getLine
        let multList = subMult num 0 k
        print (maximum multList)