n, k = gets.split.map(&:to_i)
s = gets.split("")

if s[k - 1] == "("
    match_num = 1
    i = 0
    while match_num != 0 do
        if s[k + i] == "("
            match_num += 1
        else
            match_num -= 1
        end
        i += 1
    end
    p k + i
end

if s[k - 1] == ")"
    match_num = 1
    i = 0
    while match_num != 0 do
        if s[k - 2 + i] == ")"
            match_num += 1
        else
            match_num -= 1
        end
        i -= 1
    end
    p k + i
end