#include <iostream>
using namespace std;
 
int main(){
	int X, Y, L;
	cin >> X >> Y >> L;
	if(Y == 0){
		if(X == 0){
			cout << 0 << endl;
		}else{
			cout << (abs(X / L) - 1) + 2 << endl;
		}
	}else if(Y <= 0){
		if(X == 0){
			cout << (-1 * Y - 1) / L + 3 << endl;
		}else{
			cout << (abs(X) - 1) / L + (-1 * Y - 1) / L + 3 << endl;
		}
	}else{
		if(X == 0){
			cout << (Y - 1) / L + 1 << endl;
		}else{
			cout << (abs(X) - 1) / L + (Y - 1) / L + 3 << endl;
		}
	}
}