#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10, INF = 0x3f3f3f3f, MOD = 1e9 + 7;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int a[4];
  for (int i = 0; i < 4; ++i) cin >> a[i];
  int ans = 2 * (abs(a[2] - a[0]) + abs(a[3] - a[1])) + 4;
  if (a[2] == a[0] || a[3] == a[1]) ans += 2;
  cout << ans << endl;
  return 0;
}
