/in/foo.cc: In function 'char func(int, int)':
/in/foo.cc:14:11: error: 'fl' was not declared in this scope
   cout << fl;
           ^~
/in/foo.cc:15:32: error: 'FBITREE' was not declared in this scope
  char ch2 = FBITREE((l+r)/2+1,r); 
                                ^
/in/foo.cc:16:11: error: 'fr' was not declared in this scope
   cout << fr;
           ^~
/in/foo.cc:13:7: warning: unused variable 'ch1' [-Wunused-variable]
  char ch1 = func(l,(l+r)/2); 
       ^~~
/in/foo.cc:15:7: warning: unused variable 'ch2' [-Wunused-variable]
  char ch2 = FBITREE((l+r)/2+1,r); 
       ^~~