#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long int a, p, q, l, b = 0, i, d, m, n, k, sum = 0, t = 1, x = 1, z,
                            y = 0;
  cin >> a >> b >> p >> q;
  if (a == p) {
    k = abs(b - q) * 2 + 6;
  } else if (b == q) {
    k = abs(a - p) * 2 + 6;
  } else {
    k = abs(b - q) * 2 + abs(a - p) * 2 + 4;
  }
  cout << k;
  return 0;
}
