ABCRO> A;
--- Output:
ABCRO> B;
--- Output:
ABCRO> C;
--- Output:
ABCRO> ;
--- Output:
ABCRO> A B;
--- Output: O
ABCRO> A B;
--- Output:
ABCRO> R C;
--- Output:
ABCRO> A B;
--- Output:
ABCRO> A B;
--- Output:
ABCRO> R;
--- Output:
ABCRO> C B;
--- Output:
ABCRO> A;
--- Output: O
ABCRO> A;
--- Output:
ABCRO> B;
--- Output:
ABCRO> R B;
--- Output:
ABCRO> A;
--- Output:
ABCRO> ;
--- Output:
ABCRO> B;
--- Output:
ABCRO> R;
--- Output:
ABCRO> C;
--- Output:
ABCRO> A B;
--- Output: O