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

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