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