N,K=map(int,input().split())
S=list(input())
ANS={}
queue=[]
for i in range(N):
    if S[i]==')':
        idx=queue.pop()
        ANS[idx]=i+1
        ANS[i+1]=idx
    else:# =='('
        queue.append(i+1)
print(ANS[K])