import java.util.*

fun main(args: Array<String>) {
	val scan = Scanner(System.`in`)
	val a = scan.nextInt()
	val b = scan.nextInt()
	val c = scan.nextInt()

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