#include <bits/stdc++.h>
using namespace std;
bool dist(int x1, int y1, int x2, int y2) {
  if (x1 == x2 && (y1 == y2 + 1 || y2 == y1 + 1)) return 1;
  if (y1 == y2 && (x1 == x2 + 1 || x2 == x1 + 1)) return 1;
  return 0;
}
int sameline(int x1, int y1, int x2, int y2) {
  if (x1 == x2) return 2 * (2 + abs(y1 - y2) + 1);
  if (y1 == y2) return 2 * (2 + abs(x1 - x2) + 1);
  return 0;
}
int main() {
  int x1, y1, x2, y2, tmp;
  cin >> x1 >> y1 >> x2 >> y2;
  if (dist(x1, y1, x2, y2) == 1)
    cout << 8 << endl;
  else if (tmp = sameline(x1, y1, x2, y2))
    cout << tmp << endl;
  else
    cout << 2 * (abs(x2 - x1) + 1 + abs(y2 - y1) + 1) << endl;
}
