#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, y1;
  int x2, y2;
  int sum = 0;
  cin >> x1 >> y1;
  cin >> x2 >> y2;
  int a = abs(x1 - x2);
  if (a == 0) a = 1;
  int b = abs(y1 - y2);
  if (b == 0) b = 1;
  sum += a * 2 + 2;
  sum += b * 2 + 2;
  cout << sum << endl;
  return 0;
}
