#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000

int main(){
	
	long long X,Y,L;
	cin>>X>>Y>>L;
	
	long long ans = 0LL;
	
	if(Y<0){
		ans += 2;
		ans += (abs(Y)+L-1)/L;
		ans += (abs(X)+L-1)/L;
	}
	else{
		if(X!=0)ans++;
		ans += (abs(Y)+L-1)/L;
		ans += (abs(X)+L-1)/L;
	}
	
	cout<<ans<<endl;
	
	return 0;
}