#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, aa, bb, ans = 0;
  cin >> a >> b >> aa >> bb;
  if (a == aa)
    ans += 4;
  else if (b == bb)
    ans += 4;
  if (a > aa) {
    aa--;
  } else if (a < aa) {
    aa++;
  }
  if (b > bb) {
    bb--;
  } else if (b < bb) {
    bb++;
  }
  cout << (2 * (abs(a - aa) + abs(b - bb))) + ans;
  return 0;
}
