def class_div(a,b,c)
  ac = 0
  if b == 0 then
    if a.odd? then
      ac = c
    else
      ac = 1
    end
  else
    if a.odd? then
      ac = c + 1 - b
    else
      ac = b
    end
  end
end

students, classes = gets.split.map(&:to_i)
hanako, taro = gets.split.map(&:to_i)

h = hanako / classes
hd = hanako % classes
t = taro / classes
td = taro % classes

hc = class_div(h, hd, classes)
tc = class_div(t, td, classes)

if hc == tc then
  puts "YES"
else
  puts "NO"
end