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