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