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

ans = [None for _ in range(n)]
q = []
for i in range(n):
  if s[i] == "(":
    q.append(i)
  elif s[i] == ")":
    j = q.pop()
    ans[j] = i
    ans[i] = j

print(ans[k - 1] + 1)