import strutils,sequtils

var
    N,K : int
    S : string
    cnt = 0
(N,K) = stdin.readline.split.map(parseInt)
S = stdin.readline

if S[K - 1] == ')':
    for i in 0..<K:
        if S[K - 1 - i] == ')':
            cnt += 1
        else:
            cnt -= 1
        if cnt == 0:
            echo K - i
            break
else:
    for i in K - 1..N - 1:
        if S[i] == '(':
            cnt += 1
        else:
            cnt -= 1
        if cnt == 0:
            echo i + 1
            break