#include <bits/stdc++.h>
using namespace std;
int main() {
  int x1, y1, x2, y2, l;
  cin >> x1 >> y1 >> x2 >> y2;
  if ((x1 != x2) && (y1 != y2)) {
    l = abs(x1 - x2) + 1;
    l = l + abs(y2 - y1) + 1;
    l = l + l;
    cout << l;
  } else {
    if (x1 == x2) {
      l = abs(x1 - x2) + 2;
      l = l + abs(y2 - y1) + 1;
      l = l + l;
      cout << l;
    }
    if (y1 == y2) {
      l = abs(x1 - x2) + 1;
      l = l + abs(y2 - y1) + 2;
      l = l + l;
      cout << l;
    }
  }
  return 0;
}
