n,k=map(int,input().split())
k-=1
s=input()
stack=[]
ans=[]
for i in range(n):
    if stack:
        last,ind=stack[-1][0],stack[-1][1]
        if last=='(' and s[i]==')':
            stack.pop()
            ans.append((ind,i))
        else:
            stack.append((s[i],i))
    else:
        stack.append((s[i],i))
for x,y in ans:
    if x==k:
        print(y+1)
        break
    elif y==k:
        print(x+1)
        break