#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int ans = 2 * max((abs(x1 - x2) + 1), 2) + 2 * max((abs(y1 - y2) + 1), 2);
  cout << ans << endl;
  return 0;
}
