n , k = map(int,input().split())
s = list(input())

flag = True

while flag:
	for i in range(n):
		if s[i] == "(":
			for j in range(1 , n):
				if s[i + j] == "(" or i + j > n - 1:
					break
				if s[i + j] == ")":
					s[i],s[i + j] = 0,0
					if i + 1 == k:
						ans = i + j + 1
						flag = False
					if i + j + 1 == k:
						ans = i + 1
						flag = False
					break					
print(ans)