//#include <atcoder/all>
//using namespace atcoder;
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define REP(i, n) for(int i=0; i<n; i++)
#define REPR(i, n) for(int i=n-1; i>=0; i--)
#define FOR(i, m, n) for(int i=m; i<n; i++)
#define ALL(v) v.begin(), v.end()
#define bit(n) (1LL<<(n))
#define FIX(d) fixed << setprecision(d)
using P = pair<int, int>;
using LP = pair<ll, ll>;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int INF = 1e9;
const ll LINF = (1LL<<60);

template<typename T>
vector<T> table(int n, T v) { return vector<T>(n, v); }

template <class... Args>
auto table(int n, Args... args) {
  auto val = table(args...);
  return vector<decltype(val)>(n, move(val));
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll a,b,c,d;
  cin >> a >> b >> c >> d;
  if(a==c || b==d || abs(a-c)+abs(b-d)<=3) cout << 1 << endl;
  else cout << 2 << endl;
  
  return 0;
}