#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
 ll MOD=1000000007;
 ll MOD9=998244353;
 int inf=1e9+10;
 ll INF=4e18;
 ll dy[8]={1,0,-1,0,1,1,-1,-1};
 ll dx[8]={0,1,0,-1,1,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
    return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
    return ((a > b) ? (a = b, true) : (false));
}

long long extGcd(long long a, long long b, long long &p, long long &q) {  
    if (b == 0) { p = 1; q = 0; return a; }  
    long long d = extGcd(b, a%b, q, p);  
    q -= a/b * p;  
    return d;  
}


vector<ll> factor(ll n){
    ll k=n; vector<ll> ret;
    for(int i=2;i*i<=n;i++){
        while(k%i==0){
            ret.pb(i);k/=i;
        }
    }
    if(k>1)ret.pb(k);
    return ret;
}
ll modpow(ll a,ll n, ll mod) {
  ll res = 1;
  while (n > 0) {
      if (n & 1) res = res * a % mod;
      a = a * a % mod;
      n >>= 1;
  }
  return res;
}

int main(){
    ll a,b,c,d;cin >> a >> b >> c >> d;
    if(a==c||b==d){
        cout << 1 <<endl;return 0;
    }
    /*for(int i=-5;i<=5;i++){
        for(int j=-5;j<=5;j++){

        }
    }*/
    if(abs(a-c)+abs(b-d)<=3){
        cout << 1 <<endl;return 0;
    }
    cout << 2 <<endl;
}