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

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;
  return 0;
}