Trying to understand which is more efficient.

1. Initialize unordered_set member variable as a static member variable
2. Initialize unordered_set member variable in the constructor

Is one better than the other in terms of less memory usage?

class Example
{
 private:
  enum Names
  {
   JOHN,
   MIKE,
   CHARLIE,
   TOM
  };
  static unordered_set<Names> checkNames_v1;
  unordered_set<Names> checkNames_v2;

 public:
   // Constructor
   Example()
   {
    checkNames_v2.insert(JOHN);
    checkNames_v2.insert(MIKE);
   };
};

unordered_set<Names>Example::checkNames_v1
{
  JOHN,
  MIKE
};