#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <map>
#include <set>
#include <queue>
#include <iomanip>
#include <cstring>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i,n) for (int i = 0; i < int(n);i++)
const ll INF = 1e9;

int main(){
  ll a,b,c,d;
  cin >> a >> b >> c >> d;
  c-= a;
  c = abs(c);
  d-=b;
  d = abs(d);
  int ans = 2;
  if (abs(c) + abs(d) <= 3) ans = 1;
  if (c == 0 || d == 0) ans = 1;
  cout << ans << endl;
  return 0;
}