#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int a, b, c, d;
int dx[12] = {-1, -1, 1, 1, -2, -2, -1, -1, 1, 1, 2, 2};
int dy[12] = {-1, 1, -1, 1, -1, 1, -2, 2, -2, 2, -1, 1};

int main() {
  cin >> a >> b >> c >> d;
  if (a == c || b == d) {
    cout << 1 << endl;
    return 0;
  }
  for (int i = 0; i < 12; i++) {
    if (a + dx[i] == c && b + dy[i] == d) {
      cout << 1 << endl;
      return 0;
    }
  }
  cout << 2 << endl;
  return 0;
}