#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int A,B,C,D;
  cin>>A>>B>>C>>D;
  if(A == C && B == D) cout<<0<<endl;
  else if((abs(A-C)+abs(B-D) <= 3)||(A == C || B == D)) cout<<1<<endl;
  else cout<<2<<endl;
}