#include<iostream>
#include<cmath>

using namespace std;

int main(){
    int x1, y1, x2, y2;
    cin>>x1>>y1>>x2>>y2;

    if(x1==x2 || y1==y2){
        cout<<"2"<<endl;
        return 0;
    }
    if(abs(x1-x2)==abs(y1-y2)){
        cout<<"1"<<endl;
        return 0;
    }
    cout<<"0"<<endl;
    return 0;
}