n,i = gets.split.map(&:to_i)
s = gets.chomp

q = s.chars.each_with_object(stack: [], parsed: [], counter: 0) { |v,o|
    if v == '('
        o[:counter] += 1
        o[:stack] << o[:counter]
        o[:parsed] << o[:counter]
    else
        t = o[:stack].pop
        o[:parsed] << t
    end
}
half = q[:parsed][i - 1]
q[:parsed][i - 1] = 0
puts q[:parsed].find_index(half) + 1