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