#include<stdio.h>
int main()
{

unsigned int a,b;
   int i,x,count=0;
   if(x>=0){


    scanf("%d %d %d",&a,&b,&x);
   }

    for(i=a;i<=b;i++){

        if(i%x==0)count++;
    }
    printf("%d",count);
    return 0;


}
