/in/foo.cc: In function 'int re(int)':
/in/foo.cc:27:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int find_k()':
/in/foo.cc:41:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int bfs(int)':
/in/foo.cc:59:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^