main = do
    s' <- getLine
    t  <- getLine
    let s = restore s' t
    putStrLn $ if s' /= s then map (\c->if c=='?' then 'a' else c) s
                          else "UNRESTORABLE"

restore s' t = let
    s = restore' s' t
    in if s == s' then s else restore' s t

restore' [] _ = []
restore' s' t = if canReplace s' t && length s' >= length t
 then t ++ drop (length t) s'
 else head s' : restore' (tail s') t
 where
 canReplace _ [] = True
 canReplace [] _ = False
 canReplace (x:xs) (y:ys) = (x=='?' || x==y) && canReplace xs ys
    