import java.util.*;
public class printDivisor{
public static void main(String args []){
Scanner sc = new Scanner(System.in);
int a = sc.nextInt();
int b = sc.nextInt();
int p = sc.nextInt();
int counter=0;
for(int i = a; i>=b; i++){
if(i%p == 0){
counter++;
System.out.println(counter);
}
}
System.out.println(counter);
}
}