#include <bits/stdc++.h>
using namespace std;
int main() {
  long long x1, x2, y1, y2, ans = 0;
  scanf("%lld %lld", &x1, &y1);
  scanf("%lld %lld", &x2, &y2);
  ans += 2 * (y2 - y1 == 0 ? 2 : abs(y2 - y1) + 1);
  ans += 2 * (x2 - x1 == 0 ? 2 : abs(x2 - x1) + 1);
  printf("%lld", ans);
  return 0;
}
