#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)

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