#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m, a, b;
  cin >> m >> n >> a >> b;
  long long wea;
  long double d = sqrt(pow(m - a, 2) + pow(n - b, 2));
  long double sdos = sqrt(2);
  if (d <= sdos) {
    wea = 8;
  } else {
    long long arreglo[2] = {m - a, n - b};
    for (int i = 0; i < 2; i++) {
      if (arreglo[i] == 0) {
        arreglo[i] = arreglo[i] + 1;
      }
      if (arreglo[i] < 0) {
        arreglo[i] = arreglo[i] * (-1);
      }
    }
    wea = (arreglo[0] + arreglo[1] + 2) * 2;
  }
  cout << wea;
}
