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)

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

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