java, 287 bytes

Result

AC

Duration

1665ms

Code [DL]

import java.util.*;interface A{static void main(String[]a){int i,j,w,h;Scanner s=new Scanner(System.in);h=s.nextInt();w=s.nextInt();String k="",q="*",p=" ",n="\n";for(i=0;i<w;i++)k+=q;k+=n;for(i=0;i<h-2;i++){k+=q;for(j=0;j++<w-2;)k+=p;k+=q+n;}for(i=0;i++<w;)k+=q;System.out.println(k);}}

stdin

18
97

stdout

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

stderr

strace