sqlite3, 194 bytes

Result

AC

Duration

1000ms

Code [DL]

with x(i,j,k)as(select v+0 i,substr(v,length(v+0)+1)j,1 k from i union select i,j,k+1 from x)select printf('*%.'||(j-2)||'c*',case when(k=1 or k=i)then'*'else' 'end)from x limit(select i from x)

stdin

48
64

stdout

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

stderr