N,K = map(int,raw_input().split(' '))
S = raw_input()
s = []
i = 0
flag = False
while not flag:
	while i < len(S) and S[i] == '(':
		s.append(i+1)
		i += 1
	while i < len(S) and S[i] == ')':
		p = s.pop()
		if p == K or (i+1) == K:
			flag = True
			print i+1 if p == K else p
			break
		i += 1