#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, x2, y1, y2, ans = 0;
  scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
  ans = abs(x1 - x2) + 1 + abs(y1 - y2) + 1;
  if (x1 == x2 or y1 == y2) ans++;
  printf("%d", ans << 1);
}
