#include <iostream>
#include <cstdlib>
#include <cmath>
using namespace std;

int main(){
  int x, y, l;
  while(cin >> x >> y >> l){
    int ans = 0;
    if(x != 0) ans = 1;
    if(y < 0) ans = 2;

    if(x != 0) ans += (abs(x) - 1) / l + 1;
    if(y != 0) ans += (abs(y) - 1) / l + 1;

    cout << ans << endl;
  }
}