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