#include <bits/stdc++.h>
using namespace std;

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

	int ans = 2;
	if( A == C || B == D ) ans = 1;
	if( abs(A - C) + abs( B - D ) <= 3 ) ans = 1;

	cout << ans << endl;
}