#include <bits/stdc++.h>
using namespace std;

int main(){
	long long int x,y,l;
	cin >> x >> y >> l;
	int count = 0;
	if(y < 0) count += 2;
	else if(x != 0) count++;
	x = abs(x);
	y = abs(y);
	while(x > 0){
		x -= l;
		count++;
	}
	while(y > 0){
		y -= l;
		count++;
	}
	cout << count << endl;
	return 0;
}