#include <iostream>
using namespace std;

int main() {
	int x,y,l;cin>>x>>y>>l;
	int all=0;
	if(y>0)
	{
		all+=--y/l+1;
		if(x>0)all+=--x/l+2;
		else if(x<0)x=-x,all+=--x/l+2;
	}
	else if(y<0)
	{
		if(x>0)y=-y,all+=--x/l+4+--y/l;
		else if(x<0)x=-x,y=-y,all+=--x/l+4+--y/l;
		else y=-y,all+=--y/l+3;
	}
	else
	{
		if(x>0)all+=--x/l+2;
		else if(x<0)x=-x,all+=--x/l+2;
	}
	cout<<all<<endl;
	return 0;
}