#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int x1, y1, x2, y2;
  scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
  int res = abs(x1 - x2) + 1 + (x1 == x2);
  res += abs(y1 - y2) + 1 + (y1 == y2);
  printf("%d\n", res * 2);
}
