#include <iostream>
#include <algorithm>

using namespace std;

int main(){
  int X, Y, L;
  cin >> X >> Y >> L;
  int ans = (abs(X)+L-1)/L + (abs(Y)+L-1)/L;
  if(X!=0){
	ans++;
  }else{
	if(Y<0) ans++;
  }
  if(Y<0) ans++;
  cout << ans << endl;
  
}