# frozen_string_literal: true

N, M, P, Q = gets.chomp.split.map(&:to_i)

fall = Array.new(12, M)
(P - 1..P + Q - 2).each do |i|
  fall[i] *= 2
end

remain = N
result = 1
fall.cycle.each_with_index do |f, i|
  remain -= f
  if remain <= 0
    result = i + 1
    break
  end
end

puts result