import sys
if sys.platform =='ios':
	import clipboard
	a=clipboard.get()
	a = a.split('\n')
	text = '\n'.join(a)
	with open('input_file.txt','w') as f:
		f.write(text)
	sys.stdin = open('input_file.txt')

from collections import deque
	
n,k = map(int,input().split())
s = input()
q = deque([])


for i,x in enumerate(s):
	if x == "(":
		q.append(i+1)
	else:
		y = q.pop()
		if i+1 == k:
			print(y)
		elif y == k:
			print(i+1)
			exit()