#!/usr/bin/python
# -*- coding: utf-8 -*-

### INPUT ###
N , h = map(int, raw_input().split())
arrays = raw_input()
num = []
ans = {}
for i,array in enumerate(arrays):
       	if array == "(":
       		num.append(i+1)
       	elif array == ")":
       		tmp = num.pop(-1)
       		ans.update({i+1 : tmp})
       		ans.update({tmp : i+1})
       	if h in ans:
       		print ans[h]
       		exit()