package main

import "fmt"

type Stack []int

func (s *Stack) Push(v int) {
	*s = append(*s, v)
}

func (s *Stack) Pop() int {
	ret := (*s)[len(*s)-1]
	*s = (*s)[0 : len(*s)-1]
	return ret
}

func main() {
	var N, K int
	var S string
	fmt.Scan(&N, &K)
	fmt.Scan(&S)
	s := Stack(make([]int, 0, N))
	match := make([]int, N)
	for i, r := range S {
		switch r {
		case '(':
			s.Push(i)
		case ')':
			m := s.Pop()
			match[m] = i
			match[i] = m
		}
	}
	fmt.Println(match[K-1] + 1)
}