perl, 59 bytes

Result

AC

Duration

976ms

Code [DL]

$h=<>-2;print$a="*"x($w=<>),"
",("*"." "x($w-2)."*
")x$h,$a

stdin

26
19

stdout

*******************
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*                 *
*******************

stderr