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