#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int now = 0;
  if (x1 == x2) now += 2;
  if (y1 == y2) now += 2;
  cout << now + 4 + 2 * abs(x1 - x2) + 2 * abs(y1 - y2) << endl;
}
