#include <bits/stdc++.h>
using namespace std;
const int MOD = (1e9) + 7;
const long long inf = 1e17;
const int offset = 3000;
int main() {
  int x1, x2, y1, y2;
  scanf("%d", &x1), scanf("%d", &y1), scanf("%d", &x2), scanf("%d", &y2);
  int temp = abs(x1 - x2) + abs(y1 - y2);
  if (x1 == x2 or y1 == y2) {
    cout << 2 * (temp - 1) + 8;
  } else {
    cout << 2 * (temp - 2) + 8;
  }
  return 0;
}
