answer.code: In function ‘std::vector<int> longest_trip(int, int)’:
answer.code:63:59: error: expected ‘)’ before ‘{’ token
   63 |         } else if (are_connected({v[1][0]}, {v[0].back()}) {
      |                   ~                                       ^~
      |                                                           )
answer.code:86:5: error: expected primary-expression before ‘}’ token
   86 |     }
      |     ^
answer.code:87:1: warning: control reaches end of non-void function [-Wreturn-type]
   87 | }
      | ^