#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
const ll inf = 1e16;
const ll md = 1000000007;

int main() {
  int x,y,l;
  cin>>x>>y>>l;
  int ans;
  if(x==0&&y>=0) ans=(y+l-1)/l;
  else if(y>=0) ans=(y+l-1)/l+1+(abs(x)+l-1)/l;
  else ans=(-y+l-1)/l+2+(abs(x)+l-1)/l;
  cout<<ans<<endl;
  return 0;
}