#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, y1, x2, y2;
  scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
  int xp = min(x1, x2 - 1);
  int xq = max(x1, x2 + 1);
  int yp = min(y1, y2 - 1);
  int yq = max(y1, y2 + 1);
  printf("%d\n", 2 * (xq - xp + yq - yp));
  return 0;
}
