#include <iostream>
#include <cmath>
using namespace std;
 
int main(){
	double X, Y, L;
	cin >> X >> Y >> L;
	if(Y == 0){
		if(X == 0){
			cout << 0 << endl;
		}else{
			cout << ceil(abs(X / L)) << endl;
		}
	}else if(Y < 0){
		if(X == 0){
			cout << ceil(-1 * Y / L) + 2 << endl;
		}else{
			cout << ceil(abs(X / L)) + ceil(-1 * Y / L) + 1 << endl;
		}
	}else{
		if(X == 0){
			cout << ceil(Y / L) << endl;
		}else{
			cout << ceil(abs(X / L)) + ceil(Y / L) + 1 << endl;
		}
	}
}







//4:45 一旦中断　ロボットの操縦¥
//14:20　起床