n, k = STDIN.read.split(' ').map(&:to_i)

case
when k > n
  out = 'NO'
when k == 0
  out = 'YES'
else
  max = case n % k
  when 0
    n / 2
  when 1
    n / 2 + 1
  end

  out = if k <= max
    'YES'
  else
    'NO'
  end
end

puts out
