#include <bits/stdc++.h>
using namespace std;
int main() {
  int sX, sY;
  int eX, eY;
  cin >> sX >> sY >> eX >> eY;
  if (sX == eX) sX++;
  if (sY == eY) sY++;
  cout << 2 * (abs(sX - eX) + 1 + abs(sY - eY) + 1) << "\n";
}
