$4\mathrm{.}2$ Consider a Feistel cipher composed of sixteen rounds with a block length of $128$ bits and a key length of $128$ bits. Suppose that, for a given $k,$ the key scheduling algorithm determines values for the first eight round keys, $k_1,k_2,dots{k}_8,$ and then sets

$k_9=k_8,k_{10}=k_7,k_{11}=k_6,$dots,$k_{16}=k_1$