#include <iostream>
#include <string.h>
using namespace std;
int main()
{
    long long a,b,c,counter=0;
	cin>>a>>b>>c;
	for(long long i=a;i<=b;i++)
	{
		if(i%c==0)
		{
			counter++;
		}
	}	
	cout<<counter;
	return 0;
}