/in/foo.cc: In member function 'int solve::ad(int, int)':
/in/foo.cc:24:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In member function 'int solve::add(int, int, int)':
/in/foo.cc:31:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In member function 'int solve::tarjan(int)':
/in/foo.cc:43:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^