#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <sstream>
#include <complex>
#include <ctime>
#include <cassert>
#include <functional>

using namespace std;

typedef long long ll;
typedef vector<int> VI;
typedef pair<int,int> PII;

#define REP(i,s,t) for(int i=(s);i<(t);i++)
#define FILL(x,v) memset(x,v,sizeof(x))

const int s = 2024;
bool isCorner(int x, int y) {
  return (x == 0 && y == 0) ||
    (x == s && y == 0) ||
    (x == 0 && y == s) ||
    (x == s && y == s);
}
int main() {
  int x1, y1, x2, y2, ans;
  cin >> x1 >> y1 >> x2 >> y2;
  bool c1 = isCorner(x1, y1);
  bool c2 = isCorner(x2, y2);
  if (c1 && c2) ans = 0;
  else if (c1 || c2) ans = 1;
  else ans = 2;
  cout << ans << endl;
  return 0;
}