#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 * 2;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  int ans = 0;
  if (x1 <= x2 - 1) {
    ans += (x2 - x1 - 1 + 2) * 2;
  } else if (x1 == x2) {
    ans += 4;
  } else {
    ans += (x1 - x2 - 1 + 2) * 2;
  }
  if (y1 <= y2 - 1) {
    ans += (y2 - y1 - 1 + 2) * 2;
  } else if (y1 == y2) {
    ans += 4;
  } else {
    ans += (y1 - y2 - 1 + 2) * 2;
  }
  cout << ans << "\n";
  return 0;
}
