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