
import Foundation

func main(){
   let line = (readLine()!).split(separator: " ")
   let l = Int(line[0])!
   let r = Int(line[1])!
   let d = Int(line[2])!
   
   var i = l
   var answer = 0
   while i <= r {
      if i % d == 0 {
         answer += 1
         i += d
      } else {
         i += 1
      }
   }
   print(answer)
}
main()