#include <bits/stdc++.h>
#define NIL (-1)
#define ll long long
using namespace std;
const double PI = acos(-1.0);

int main() {
	ll A, B, C, D;
	cin >> A >> B >> C >> D;

	if (A == C || B == D) cout << 1 << endl;
	else if (abs(A - C) + abs(B - D) <= 3) cout << 1 << endl;
	else cout << 2 << endl;
}