#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main() {
  int x,y,l,ans=0;
  cin>>x>>y>>l;
  x=abs(x);
  y=abs(y);
  if(x%l==0)
	  ans+=x/l;
  if(y%l==0)
	  ans+=y/l;
  if(y%l!=0){
  	ans+=y/l+1;
  }
  if(x%l!=0){
  	ans+=x/l+1;
  }
  if(x==0 || y==0)
    cout<<ans<<endl;
  else cout<<ans+1<<endl;
}