#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cstdio>

using namespace std;

int A,B,i,j,d,ans=0;

int gcd()
{
	int a=i,b=j;
	if (a<b) swap(a,b);
	while (b)
	{
		a=a%b;
		swap(a,b);
	}
	return a;
}

int main()
{
	freopen("parents.in","r",stdin);
	freopen("parents.out","w",stdout);
	scanf("%d%d%d",&A,&B,&d);
	for (i=d;i<=A;i+=d)
		for (j=d;j<=B;j+=d)
			if (gcd()==d) ++ans;
	printf("%d\n",ans);
	return 0;
}