$(13\%)$ Write a function void under $($int s$)$ that prints an "underwear" of size s$.$ You can assume that $s$ is even and $s4.$ There shall be s rows of printings. The top and bottom rows shall have $2s$ and $s\text{'}***\text{'}$ symbols respectively. The following shows some example printing outputs for various function calls. $($You may use to denote a space in your answer for clarity.$)$

$\backslash$table$[[$under $(4),$under $(6),$under $(10)],[,,]]$