fun main(args: Array<String>) {
  val (N, K) = readLine()!!.split(" ").map{ x -> x.toInt() }
  val se     = readLine()!!
  val start  = se[K-1]
  if(start == '(') {
    var c = 0
    for(i in (K..N) ) {
      if(se[i] == '(') c++
      else{
        if(c==0) {
          println(i+1)
          break
        }else{
          c--
        }
      }
    }
  } else if( start == ')') {
    var c = 0
    for(i in (K-2 downTo 0) ) {
      if(se[i] == ')') {
        c++
      }
      else{
        if(c==0) {
          println(i+1)
          break
        }else{
          c--
        }
      }
    }
  }
}