#include <bits/stdc++.h>
#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
#include<string>
using namespace std;


int main()
{
    long long a, b, c, d;
    cin >> a >>  b >> c >> d;
    bool yes = false;
    c -= a;
    d -= b;
    if ((abs(c)+abs(d))<=3) yes = true;
    else if (c == 0 || d == 0) yes = true;
    cout << ((yes) ? 1 : 2) << endl;
}