//g++ 1.cpp -std=c++14 -I .
#include <bits/stdc++.h>
using namespace std;

/*
#include <atcoder/all>
using namespace atcoder;
*/

using ll = long long;
using ld = long double;
#define fi first
#define se second
#define pb push_back

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