#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  if ((fabs(a - c) == 1 && fabs(b - d) == 0) ||
      (fabs(a - c) == 0 && fabs(b - d) == 1)) {
    cout << 2 * (fabs(a - c) + fabs(b - d)) + 4 + 2;
  } else if (a == c || b == d) {
    cout << 2 * (fabs(a - c) + fabs(b - d)) + 4 + 2;
  } else {
    cout << 2 * (fabs(a - c) + fabs(b - d)) + 4;
  }
}
