python3, 77 bytes

Result

WA

Duration

976ms

Code [DL]

i=input
h=int(i())
w=int(i())
s='*'*w+'\n'
print(s+('A'+' '*(w-2)+'A\n')*h+s)

stdin

70
18

stdout

******************
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
A                A
******************

stderr