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

int main() {
  int A, B, C, D; cin >> A >> B >> C >> D;
  if(abs(C-A)+abs(D-B) <= 3 or A==C or B==D) cout << 1 << endl;
  else cout << 2 << endl;
}