inpt = map(int, raw_input().split())
n = inpt[0]
k = inpt[1]
s = raw_input()
ansmemo = []
for i in range(0, n+1):
	ansmemo.append(0)
stack = []

for i in range(0, len(s)):
	if s[i] == '(':
		stack.append(i+1)
	else:
		x = stack.pop(-1)
		ansmemo[i+1] = x
		ansmemo[x] = i+1

print ansmemo[k]