#include <stdio.h>








int main()
{
    unsigned long long int n ,b ,a;
    scanf("%llu %llu %llu",&a,&b,&n);
    int z = 0;


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


        if ( i%n == 0)
        {
            z++;
        }




    }
    printf("%d\n",z);
    return 0;



}
