#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <numeric>
#include <bitset>
#define rep(x, to) for (int x = 0; x < (to); x++)
#define REP(x, a, to) for (int x = (a); x < (to); x++)
#define foreach(itr, x) for (typeof((x).begin()) itr = (x).begin(); itr != (x).end(); itr++)

using namespace std;

typedef long long ll;
typedef pair<int, int> PII;
typedef pair<long, long> PLL;

ll x, y;
ll x2, y2;
ll ans;


ll diff(ll s, ll t, ll p, ll q) {
	ll res = (s*s + t*t) - (p*p + q*q);
	return res;
}

int main() {
	cin >> x >> y;
	cin >> x2 >> y2;

	ll tmp = min(abs(x), abs(y));
	ans = tmp + (abs(x)-tmp) + (abs(y)-tmp);
	
	// 途中に歩兵
	if (diff(x, y, x2, y2) > 0) {
		//1直線じょうにある
		ll dot = x * x2 + y * y2;
		ll cross = x * x2 - y * y2;
		if (dot > 0 && cross == 0) {
			// まっすぐ直線状
			if (x == 0 || y == 0) ans += 2;
			// 対角線上(45)
			else if (abs(x) == abs(y)) ans += 1;
		}
	}
	cout << ans << endl;



	return 0;
}