#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;

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 (x * x2 + y * y2 > 0 && x * x2 - y * y2 == 0) {
		ans += 2;
	}

	cout << ans << endl;



	return 0;
}