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 OCaml (4.02.3) (judge verdict: Accepted)

open String
let rec iter a b f = if a >= b then [] else let v = f a in v :: iter (a+1) b f
let check a b =
  iter 0 (length a) (fun i -> a.[i] = '?' || a.[i] = b.[i])
  |> List.fold_left (&&) true
let () =
  Scanf.scanf "%s %s" @@ fun s' t ->
  let s'_len, t_len = length s', length t in
  iter 0 (s'_len-t_len+1) (fun i ->
    if check (sub s' i t_len) t then
      sub s' 0 i ^ t ^ sub s' (i+t_len) (s'_len-i-t_len)
      |> map (function '?' -> 'a' | c -> c)
      |> fun s -> Some s
    else
      None)
  |> List.fold_left (fun r -> function None -> r | Some s -> s) "UNRESTORABLE"
  |> print_endline