answer.code: In function ‘int min_cardinality(int)’:
answer.code:118:52: error: expected ‘)’ before ‘{’ token
  118 |                         if(st2.find(i) == st2.end(){
      |                           ~                        ^
      |                                                    )
answer.code:124:17: error: expected primary-expression before ‘}’ token
  124 |                 }
      |                 ^