rust, 186 bytes

Result

AC

Duration

1188ms

Code [DL]

use std::io::*;fn main(){let i=&mut[0;9];stdin().read(i);let(h,w)=((i[0]-48)*10+i[1]-48,(i[3]-48)*10+i[4]-50);for i in 1..=h{println!("*{}*",if i==1||i==h{"*"}else{" "}.repeat(w as _))}}

stdin

88
77

stdout

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

stderr

warning: unused `std::result::Result` which must be used
 --> /tmp/code.rs:1:42
  |
1 | use std::io::*;fn main(){let i=&mut[0;9];stdin().read(i);let(h,w)=((i[0]-48)*10+i[1]-48,(i[3]-48)*10+i[4]-50);for i in 1..=h{println!("*{}*",if i==1||i==h{"*"}else{" "}.repeat(w as _))}}
  |                                          ^^^^^^^^^^^^^^^^
  |
  = note: #[warn(unused_must_use)] on by default
  = note: this `Result` may be an `Err` variant, which should be handled