N,K = map(int,input().split())
K -= 1
S = input().strip()
stk = []
for i in range(N):
    if len(stk)>0 and stk[-1][0]=="(":
        if S[i]==")":
            if i==K or stk[-1][1]==K:
                if i==K:
                    print(stk[-1][1]+1)
                else:
                    print(i+1)
                break
            stk.pop()
        else:
            stk.append((S[i],i))
    else:
        stk.append((S[i],i))