def kakko(N, K, S):
    K = K - 1
    S = list(S)
    cnt = 1
    if S[K] == '(':
        i = K + 1
        while len(S) > 0:
            if S[K + 1] == ')':
                break
            elif (S[i] == '(') and (S[i + 1] == ')'):
                S.pop(i)
                S.pop(i)
                cnt += 2
                i -= 1
            else:
                i += 1
        return K + cnt + 1
    elif S[K] == ')':
        i = K - 1
        while len(S) > 0:
            if S[i] == '(':
                break
            elif (S[i] == ')') and (S[i - 1] == '('):
                S.pop(i)
                S.pop(i - 1)
                cnt += 2
                i -= 2
            else:
                i -= 1
        return K - cnt + 1

if __name__ == '__main__':
    N, K = map(int, input().split())
    S = input()
    print(kakko(N, K, S))