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

l = [1]
d = 1
for i in range(1, len(s)):
    if s[i-1] == '(' and s[i] == '(':
        d += 1
        l.append(d)
    elif s[i-1] == ')' and s[i] == ')':
        d -= 1
        l.append(d)
    else:
        l.append(d)
# print(l)

lk = l[k-1]
# print(lk)

sk = s[k-1]
# print(sk)

if sk == '(':
    l2 = l[lk:]
    # print(l2)
    x = l2.index(lk)
    print(x+1 + k)
else:
    l2 = l[:k-1][::-1]
    # print(l2)
    x = l2.index(lk)
    print(k - (x+1))