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