#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int uppery = y2 + 1;
  int lowery = y2 - 1;
  int upperx = x2 + 1;
  int lowerx = x2 - 1;
  int ans = 4;
  ans +=
      abs(x1 - upperx) + abs(y1 - lowery) + abs(x1 - lowerx) + abs(y1 - uppery);
  cout << ans << endl;
  return 0;
}
