#include<bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
#define vec vector<ll>
#define mat vector<vector<ll> >
#define fi first
#define se second
#define double long double
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
//typedef long double ld;
typedef complex<double> Complex;
const ll INF=1e9+7;
const ll MOD=998244353;
const ll inf=LONG_MAX;
const ll mod=INF;
const ll MAX=140010;


signed main(){
    ll a,b,c,d;cin>>a>>b>>c>>d;
    ll ans=2;
    if(a==c||b==d)ans=1;
    if(a==c&&b==d)ans=0;
    if(abs(a-c)+abs(b-d)<=3)ans=1;
    cout<<ans<<endl;
}