#include "bits/stdc++.h"

#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 1000000007;


signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int A, B, C, D; cin >> A >> B >> C >> D;
	if (A == C || B == D || abs(A - C) + abs(B - D) <= 3) {
		cout << 1 << endl;
	}
	else {
		cout << 2 << endl;
	}
	return 0;
}