#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int d = 2 * (abs(x2 - x1) + abs(y2 - y1));
  if (x1 == x2 || y1 == y2)
    cout << d + 6 << endl;
  else
    cout << d + 4 << endl;
  return 0;
}
