#include <iostream>
#include <cmath>
using namespace std;
int main () {
    int a, b, c, d;
    while (cin >> a >> b >> c >> d, a) {
        if (a==c && b==d)
            cout << 0 << endl;
        else if ( abs(a-c)==2 && abs(b-d)==2 || (a==c) || (b==d) ) 
            cout << 1 << endl;
        else cout << 2 << endl;
    }
    return 0;
}

#include 
#include 
using namespace std;
int main () {
    int a, b, c, d;
    while (cin >> a >> b >> c >> d, a) {
        if (a==c && b==d)
            cout << 0 << endl;
        else if ( abs(a-c)==2 && abs(b-d)==2 || (a==c) || (b==d) )  <<------------- bad logic
            cout << 1 << endl;
        else cout << 2 << endl;
    }
    return 0;
}

bad logic at the line indicated.