#include <bits/stdc++.h>
using namespace std;
int x1, x2, x3;
int Y1, y2, y3;
int main() {
  cin >> x1 >> Y1 >> x2 >> y2;
  x3 = (x1 <= x2 ? x2 + 1 : x2 - 1);
  y3 = (Y1 <= y2 ? y2 + 1 : y2 - 1);
  int r = 0;
  if (x1 == x2 || Y1 == y2) r = 2;
  cout << r + 2 * abs(x1 - x3) + 2 * abs(Y1 - y3);
  return 0;
}
