#include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define ll long long
int main(){
    ll a, b, c, d;
    cin >> a >> b >> c >> d;
    if (abs(a-c) + abs(b-d) <= 3 || a == c || b == d) cout << 1 << endl;
    else cout << 2 << endl;
}