#include <bits/stdc++.h>
int main() {
  int a, b, c, d;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int ans = 2 * abs(a - c) + 2 * abs(b - d) + 4;
  if (a == c) ans += 2;
  if (b == d) ans += 2;
  printf("%d", ans);
}
