n,k=map(int,input().split())
s=[(i+1,j) for i,j in enumerate(input())]
stack=[]
if s[k-1][1]=='(':
    for i,j in s:
        if j=='(':
            stack.append(i)
        else:
            n=stack.pop()
            if n==k:
                print(i)
                exit()
else:
    for i,j in s:
        if j=='(':
            stack.append(i)
        else:
            if i==k:
                print(stack[-1])
                exit()
            stack.pop()