Find last two elemans "00"

w =   


    

    Logic
    

    
    

        

            

                
                0
                1
            

            

                > A
                B
                A
            

            

                 B
                C
                A
            

            

                * C
                C
                A
            

        


        

    

    

        

            

                
                0
                1
            

            

                > a
                b
                a
            

            

                 b
                c
                a
            

            

                * c
                ϕ
                ϕ