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

int main(){
  int X, Y, L;
  cin >> X >> Y >> L;
  int result;

  //count turn
  if(Y < 0){
    result = 2;
  } else if(X == 0){
    result = 0;
  } else{
    result = 1;
  }

  result += ceil((double) abs(X) / L);
  result += ceil((double) abs(Y) / L);

  cout << result << endl;
}