import Foundation

let input_line: String = readLine()!
let split: [String] = input_line.components(separatedBy: " ")

let a = Int(split[0])!
let b = Int(split[1])!
let c = Int(split[2])!
var num = 0


for i in a...b {
  if (i%c) == 0 {
    num += 1
  }
}
print(num)
