#include <iostream>
#include <string>
#include <cmath>
#include <cstdlib>

using namespace std;

int main() {
  int x, y, l, count=0;

  cin >> x >> y >> l;

  if(y >= 0){
    if(x != 0){
      count++;
    }
  }else{
    if(x != 0){
      count= count+2;
    }
  }
  count = count + abs(y)/l;
  if(abs(y)%l != 0){
    count++;
  }

  count = count + abs(x)/l;
  if(abs(x)%l != 0){
    count++;
  }

  cout << count << endl;

  return 0;
}