/in/foo.cc: In function 'int er_fen(int, int)':
/in/foo.cc:21:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int mid = l+r>>1;
             ~^~
/in/foo.cc:30:2: error: expected ';' before 'return'
  return ;
  ^~~~~~
/in/foo.cc:31:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^