#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, a, d, p;
  cin >> n >> m >> a >> d;
  p = max(a, n);
  a = min(a, n);
  n = p;
  p = max(m, d);
  d = min(m, d);
  m = p;
  if (n != a && m != d) {
    p = 2 * abs(n - a + 1) + 2 * abs(m - d + 1);
    cout << p;
  }
  if (n == a && m != d || n != a && m == d) {
    p = 2 * abs(n - a + 1) + 2 * abs(m - d + 1);
    cout << p + 2;
  }
  if (n == a && m == d) {
    p = 2 * abs(n - a + 1) + 2 * abs(m - d + 1);
    cout << p + 3;
  }
  return 0;
}
