fun member x nil = false
  | member x (h::tl) =
    if x = h
    then true
    else member x tl


fun readInt () =
    valOf (TextIO.scanStream (Int.scan StringCvt.DEC) TextIO.stdIn)


fun readStr () =
    let
        fun scan reader stream = SOME (StringCvt.splitl (not o Char.isSpace) reader (StringCvt.skipWS reader stream))
    in
        valOf (TextIO.scanStream scan TextIO.stdIn)
    end


fun findAns k s =
    let
        fun makePairs _ [] _ = []
          | makePairs i (h::tl) stack = 
            if h = #"(" then makePairs (i + 1) tl (i :: stack)
            else (* #")" *) [List.hd stack, i] :: makePairs (i + 1) tl (List.tl stack)

        val pairs = makePairs 1 (String.explode s) []
        val included = valOf (List.find (fn pair => member k pair) pairs)
    in
        if List.hd included = k then List.nth (included, 1)
        else List.nth (included, 0)
    end


val () =
    let
        val n = readInt ()
        val k = readInt ()
        val s = readStr ()

        val ans = findAns k s
    in
        print (Int.toString ans ^ "\n")
    end