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

int main(){
  int x, y, l;
  cin >>x>>y>>l;

  double c;
  c = abs( (double)y / l );
  c = ceil(c);

  if(x!=0){
    c ++;
    
    c += abs( (double)x/l );
    c = ceil(c);
  }
  
  cout << c << endl;
  
  return 0;
}