main.cpp: In function 'int main()':
main.cpp:37:29: error: no matching function for call to 'Set::Set()'
         Set s1(v1), s2(v2), s3;
                             ^~
In file included from main.cpp:16:0:
set.h:63:14: note: candidate: Set::Set(std::vector<long int>)
     explicit Set(std::vector<int64_t> array) {
              ^~~
set.h:63:14: note:   candidate expects 1 argument, 0 provided
set.h:5:7: note: candidate: Set::Set(const Set&)
 class Set {
       ^~~
set.h:5:7: note:   candidate expects 1 argument, 0 provided