#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, x2, y1, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int d1 = abs(x1 - x2) + 1;
  int d2 = abs(y1 - y2) + 1;
  bool flag = (x1 == x2 || y1 == y2);
  cout << 2 * (d1 + d2 + flag);
  return 0;
}
