#include <cstdio>
using namespace std;

int main()
{
    unsigned long long int a,b,x;

   int count=0;

   scanf("%llu %llu %llu",&a,&b,&x);
    for(;a<=b;++a)
        if(a%x==0 )
         count++;
    printf("%d",count);
    return 0;
}
