Problem:
Score : 300 points

Problem Statement

E869120 found a chest which is likely to contain treasure.

However, the chest is locked. In order to open it, he needs to enter a string S consisting of lowercase English letters.

He also found a string S', which turns out to be the string S with some of its letters (possibly all or none) replaced with ?.

One more thing he found is a sheet of paper with the following facts written on it:

Condition 1: The string S contains a string T as a contiguous substring.

Condition 2: S is the lexicographically smallest string among the ones that satisfy Condition 1.

Print the string S.

If such a string does not exist, print UNRESTORABLE.

Constraints

1 \leq |S'|, |T| \leq 50

S' consists of lowercase English letters and ?.

T consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S
T'

Output

Print the string S.

If such a string does not exist, print UNRESTORABLE instead.

Sample Input 1

?tc????
coder

Sample Output 1

atcoder

There are 26 strings that satisfy Condition 1: atcoder, btcoder, ctcoder,..., ztcoder.
Among them, the lexicographically smallest is atcoder, so we can say S = atcoder.

Sample Input 2

??p??d??
abc

Sample Output 2

UNRESTORABLE

There is no string that satisfies Condition 1, so the string S does not exist.

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)

import Data.List

main = do
    s' <- getLine
    t  <- getLine
    let s = restore (reverse s') (reverse t)
    putStrLn $ if canRestore s' t 
        then reverse $ 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

canRestore [] _ = False
canRestore (s:ss) key = canReplace (s:ss) key || canRestore ss key

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