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

int main(void){
    int X;
    cin >> X;
    int Y;
    cin >> Y;
    int L;
    cin >> L;
    int A=0;
    if(Y>0){
        A+=(Y+L-1)/L;
    }
    if(X!=0 || Y<0){
        A+=1;
    }
    A+=(abs(X)+L-1)/L;
    if(Y<0){
        A+=1;
        A+=(-Y+L-1)/L;
    }
    cout << A << endl;
	return 0;
}