#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int a,b,c,d;cin>>a>>b>>c>>d;
  bool bo=false;
  if(a==c||b==d){
    bo=true;
  }
  if(abs(a-c)+abs(b-d)<=3){
    bo=true;
  }
  cout<<(bo==true?1:2)<<endl;
}