#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
#define rep(i,s,n) for(ll i = s; i < (ll)(n); i++)
#define Rep(i,s,n) for(int i = s-1;i >= (int)(n); i--)

int main() {
	int sx, sy, gx, gy,dist;
	cin >> sx >> sy >> gx >> gy;
	dist = min(abs(sx + sy - gx - gy), abs(sx - sy - gx + gy));
	if (sx == gx && sy == gy) cout << 0 << endl;
	else if (sx + sy == gx + gy || sx - sy == gx - gy || abs(sx - gx) + abs(sy - gy) <= 3) cout << 1 << endl;
	else if ((sx + sy + gx + gy) % 2 == 0 || dist <= 3) cout << 2 << endl;
	else if (abs(sx - gx) + abs(sy - gy) <= 6) cout << 2 << endl;
	else cout << 3 << endl;
}
//*
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
//*/
 
#include <bits/stdc++.h>
 
// #include <atcoder/all>
 
using namespace std;
// using namespace atcoder;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl;
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
typedef long long ll;
#define int ll
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(int)(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
void YES(bool t=true) {cout<<(t?"YES":"NO")<<endl;}
void Yes(bool t=true) {cout<<(t?"Yes":"No")<<endl;}
void yes(bool t=true) {cout<<(t?"yes":"no")<<endl;}
void NO(bool t=true) {cout<<(t?"NO":"YES")<<endl;}
void No(bool t=true) {cout<<(t?"No":"Yes")<<endl;}
void no(bool t=true) {cout<<(t?"no":"yes")<<endl;}
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
#define Sp(p) cout<<setprecision(25)<< fixed<<p<<endl;
// int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
// int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {0, 1, 0, -1}, dy = {-1, 0, 1, 0};
// vi dx2 = { 1,1,0,-1,-1,-1,0,1 }, dy2 = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
const ll MOD = 1000000007;
// const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'

int calc(pll xy1, pll xy2) {
    int ans = inf;
    if (xy1 == xy2) ans = 0;
    else if (xy1.first + xy1.second == xy2.first + xy2.second) ans = 1;
    else if (xy1.first - xy1.second == xy2.first - xy2.second) ans = 1;
    else if ((xy1.first + xy1.second) % 2 == (xy2.first + xy2.second) % 2) ans = 2;

    for (int dy = -3; dy <= 3; dy++) {
        for (int dx = -3; dx <= 3; dx++) {
            int add = 1;
            if (dy == 0 and dx == 0) add = 0;
            pll xy = xy1;
            xy.first += dx;
            xy.second += dy;
            if (xy == xy2) chmin(ans, add);
        }
    }
    return ans;
}

signed main() {
    fio();

    pll xy1, xy2;
    cin >> xy1.first >> xy1.second >> xy2.first >> xy2.second;
    xy1.first += 10; xy1.second += 10;
    xy2.first += 10; xy2.second += 10;
  
    ll ans = INF;
    for (int dy = -3; dy <= 3; dy++) {
        for (int dx = -3; dx <= 3; dx++) {
            if (abs(dy) + abs(dx) > 3) continue;
            int add = 1;
            if (dy == 0 and dx == 0) add = 0;
            pll xy = xy1;
            xy.first += dx;
            xy.second += dy;
            add += calc(xy, xy2);
            chmin(ans, add);
        }
    }
    cout << ans << endl;
}