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