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