#include <bits/stdc++.h>
using namespace std;
long long n, m, t, k, mx, mn = 1e9 + 5, a, b, c, z, cnt, ans;
int main() {
  int x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  ans = (abs(x1 - x2) + abs(y1 - y2) + 2) * 2;
  if (x1 == x2 or y1 == y2) {
    ans += 2;
  }
  cout << ans << "\n";
}
