#include <bits/stdc++.h>
using namespace std;
void mod1(long long int &a) { a %= 1000000007; }
void mod2(long long int &a) {
  a %= 1000000007;
  if (a < 0) {
    a += 1000000007;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  {
    int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    int t1 = abs(x1 - x2), t2 = abs(y1 - y2);
    int t3 = (t1 + t2) * 2 + 4;
    if (x1 == x2 || y1 == y2) t3 += 2;
    cout << t3;
  }
  return 0;
}
