#include <iostream>
#include <cstdint>
#include <cmath>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	int64_t A, B, C, D;
	cin >> A >> B >> C >> D;

	if (A == C || B == D || abs(A - C) + abs(B - D) <= 3) cout << "1\n";
	else cout << "2\n";

	return 0;
}