line = gets.chomp.split(" ").map(&:to_i)
# line = [6, 20 , 7]

l = line[0]
# l = 6
r = line[1]
# r = 20
d = line[2]


d_count = 0

(l..r).each do |num|
  if num % d === 0
    d_count += 1
  end
end

puts d_count

