#! ruby
# yukicoder My Practice
# author: Leonardone @ NEETSDKASU

N, K = gets.chomp.split.map(&:to_i)
S = gets.chomp

stk = []

S.size.times do |i|
    if S[i] == '('
        stk.push i
    else
        j = stk.pop
        if K == j + 1
            puts (i + 1)
            exit
        elsif K == i + 1
            puts (j + 1)
            exit
        end
    end
end