fun main(args: Array<String>) {
    val (n,k) = readLine()!!.split(" ").map { it.toInt() }
    val s = readLine()!!
    val list = mutableListOf<Kakko>()
    s.indices.forEach { list.add(Kakko(it, s[it] == '(')) }
    var ans = -1
    while (list.isNotEmpty()) {
        val idx = list.indexOfLast { it.isLeft }
        val right = list[idx + 1]
        val left = list[idx]
        if(right.index == k - 1) {
            ans = left.index
            break
        } else if(left.index == k - 1) {
            ans = right.index
            break
        }
        list.removeAt(idx + 1)
        list.removeAt(idx)
    }
    println(ans + 1)
}

class Kakko(val index:Int, val isLeft:Boolean)