#include <bits/stdc++.h>
using namespace std;
int st(int x, int pos) { return x = x | (1 << pos); }
int Reset(int x, int pos) { return x = x & ~(1 << pos); }
int main() {
  long long x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  if (x1 == x2) {
    cout << 4 + 2 * (abs(y1 - y2) + 1) << endl;
  } else if (y1 == y2) {
    cout << 4 + 2 * (abs(x1 - x2) + 1) << endl;
  } else
    cout << (abs(x1 - x2) + 1 + abs(y1 - y2) + 1) * 2 << endl;
}
