sqlite3, 152 bytes

Result

AC

Duration

913ms

Code [DL]

with x as(select v,v k from i union select v,k-1 from x where k-1)select printf('*%.'||(substr(v,3)-2)||'c*',case when k in(1,v)then'*'else' 'end)from x

stdin

29
52

stdout

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

stderr