design a combinational circuit that takes $3$ inputs i$3,$ i$2$ and i$1$ and $2$ outputs a and b$.$ the outputs are defined as follows. $$ the output indicates the index of the input which is high. if i$3$ is $1,$ i$2$ is $0$ and i$1$ is $0$ then the output is $11.$ if $2$ inputs are high, then the highest index is the output. $$ if all inputs are low, then the output is low.