#include <bits/stdc++.h>
using namespace std;
vector<int> vec[1001];
vector<bool> vis;
int main() {
  int tc, cse = 0;
  {
    int x, y, m, n;
    cin >> x >> y >> n >> m;
    int dis1 = abs(x - n);
    int dis2 = abs(y - m);
    dis1++, dis2++;
    if (x == n or y == m)
      cout << dis1 * 2 + dis2 * 2 + 2 << "\n";
    else
      cout << dis1 * 2 + dis2 * 2 << "\n";
  }
}
