#include <stdio.h>

//メイン関数
int main(void){
  int a, b, c;
  int count = 0;
  scanf("%d %d %d", &a, &b, &c);
  for(int i = a; i <= b; i++){
    if(i%c == 0){
      count++;
    }
  }
  printf("%d", count)
}

