#include <stdio.h>
#include <stdlib.h>

int main()
{
int a, b, c,count=0;
int i,j;
scanf("%d %d %d",&a,&b,&c) ;
for(i=a;i<=b;i++)
{
    if (i%c==0)
    count=count+1;



}

printf("%d\n",count);



return 0;
}
