#include <bits/stdc++.h>
int main() {
  int a, b, a1, b1;
  scanf("%d%d", &a, &b);
  scanf("%d%d", &a1, &b1);
  int ans = 2 * (abs(a - a1) + abs(b - b1) + 2);
  if (a == a1) ans += 2;
  if (b == b1) ans += 2;
  printf("%d", ans);
}
