View Compilation Error

0_0_39399344_30412.cpp: In member function 'void Tarjan::tarjan(int, int)':
0_0_39399344_30412.cpp:57:32: error: 'son' was not declared in this scope; did you mean 'sin'?
   57 |                 tarjan(to,x),++son;
      |                                ^~~
      |                                sin