#include <bits/stdc++.h>
#define rep(i,n) for(ll (i)=0;(i)<(n);(i)++)
#define repi(i,a,b) for(ll (i)=(a);(i)<(b);(i)++)
#define SIZE_OF_ARRAY(array)    (sizeof(array)/sizeof(array[0]))
typedef long long ll;
using namespace std;
int main(){
  double X,Y,L;
  cin >> X >> Y >> L;
  int sum = 0;
  if(X==0 && Y==0){
    cout << 0 << endl;
    return 0;
  }else if(X==0 && Y>0){
    sum = 0;
  }else if(X==0 && Y<0){
    sum += 2;
  }else if(Y>=0){   
    sum += 1;
  }else{
    sum += 2;
  }

  X = ceil(abs(X)/L);
  Y = ceil(abs(Y)/L);
  sum += X+Y;
  cout << sum << endl;
  return 0;
}