Q58

A circuit outputs a digit in the form of $4$ bits. $0$ is represented by $0000, 1$ by $0001, \ldots, 9$ by $1001$. A combinational circuit is to be designed which takes these $4$ bits as input and outputs $1$ if the digit $\geq$ $5$, and $0$ otherwise. If only $\textsf{AND}, \textsf{OR}$ and $\textsf{NOT}$ gates may be used, what is the minimum number of gates required?