#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;

typedef long long ll;

int main() {
    ll 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";
}