The circuit shown in figure converts

The circuit shown in figure has 4 boxes each described by inputs P, Q, R and outputs Y, Z with
Y = $$\,P \oplus \,Q\, \oplus \,R$$
z= $$RQ + \overline P R\, + Q\,\overline P $$ The circuit acts as a

With out any additional circuitry, an 8:1 MUX can be used to obtain

A 0 to 6 counter consist of 3 flip-flops and a combination circuit of 2 input gate(s). The combination circuit consists of