$1\mathrm{.}39($a$)A=101010$ and $B=011101$ are $1\text{'}$s complement numbers. Perform the following operations and indicate whether overflow occurs.

$($i$)A+B$

$($ii$)A-B$

$($b$)$ Repeat part $($a$)$ assuming the numbers are $2\text{'}$s complement numbers.