#include<stdio.h>
int main()
{
   long long int a,b,c,cnt=0,i;
   scanf("%lld %lld %lld",&a,&b,&c);
   for(i=a;i<=b;i++)
   {
       if(i%c==0)
       {
           cnt++;
       }
   }
   printf("%lld\n",cnt);
   return 0;

}
