#include <bits/stdc++.h>
using namespace std;

int main(){
    long long 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;
}