main.cpp: In function 'int main()':
main.cpp:78:17: error: 'std::vector<long int> Set::Data' is private within this context
         v3 = s3.Data();
                 ^~~~
In file included from main.cpp:16:0:
set.h:7:26: note: declared private here
     std::vector<int64_t> Data;
                          ^~~~
main.cpp:78:22: error: no match for call to '(std::vector<long int>) ()'
         v3 = s3.Data();
                      ^