#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int ans = 0;
  if (x1 <= x2 - 1)
    ans += (x2 + 1 - x1) * 2;
  else if (x1 >= x2 + 1)
    ans += (x1 + 1 - x2) * 2;
  else
    ans += 4;
  if (y1 <= y2 - 1)
    ans += (y2 + 1 - y1) * 2;
  else if (y1 >= y2 + 1)
    ans += (y1 + 1 - y2) * 2;
  else
    ans += 4;
  cout << ans << "\n";
  return 0;
}
