#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    int a, b, c, d;
    cin >> a >> b >> c >> d;

    a -= c;
    b -= d;

    int r = 2;
    if (a == 0 || b == 0 || abs(a) + abs(b) <= 3) r = 1;

    cout << r << endl;

    return 0;
}