The combinational circuit shown on the right performs theB A subtraction operation on two signed integers, A and B$,$ as$84$ explained in the table given below and determines if this operation causes an overflow or not. $$ A is a $4-$bit integer $($A$=$A$3$ A$2$ A$1$ A$0).$X $$ B is an $8-$bit integer $($B$=$B$7$ B$6$ B$5$ B$4$ B$3$ B$2$ B$1$ B$0).$ The input X determines direction of the operation, and the value of the output V is O $0,$ if there is no overflow, andV O $1,$ if there is overflow after the operation. X Operation $0$ A$-$B $1$ B$-$A Hint: This circuit contains three parts for the following functions: $1)$ Extending the shorter integer,