#include <iostream>
#include <cmath>
using namespace std;

int main(){
    long long 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;
}