N,K = map(int,input().split())
S = list(input())
ls = []
pair = [-1]*(N)
for i in range(N):
    ls.append((S[i],i))
    if len(ls) >= 2:
        if ls[-1][0] == ')' and ls[-2][0] == '(':
            pair[ls[-1][1]] = ls[-2][1]
            pair[ls[-2][1]] = ls[-1][1]
            ls.pop()
            ls.pop()
print(pair[K-1]+1)