Buggy python submission (verdict: Runtime Error):
LEEEE
#from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from fractions import gcd
from itertools import combinations,permutations,accumulate, product # (string,3) 3回
#from collections import deque
from collections import deque,defaultdict,Counter
import decimal
import re
import math
#import bisect
#
#    d = m - k[i] - k[j]
#    if kk[bisect.bisect_right(kk,d) - 1] == d:
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#
# my_round_int = lambda x:np.round((x*2 + 1)//2)
# 四捨五入g
import sys
sys.setrecursionlimit(10000000)
#mod = 10**9 + 7
#mod = 9982443453
mod = 998244353
def readInts():
  return list(map(int,input().split()))
def I():
  return int(input())
#from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from fractions import gcd
from itertools import combinations,permutations,accumulate, product # (string,3) 3回
#from collections import deque
from collections import deque,defaultdict,Counter
import decimal
import re
import math
#import bisect
#
#    d = m - k[i] - k[j]
#    if kk[bisect.bisect_right(kk,d) - 1] == d:
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#
# my_round_int = lambda x:np.round((x*2 + 1)//2)
# 四捨五入g
import sys
sys.setrecursionlimit(10000000)
#mod = 10**9 + 7
#mod = 9982443453
mod = 998244353
def readInts():
  return list(map(int,input().split()))
def I():
  return int(input())
S = input()
T = input()
if len(S) < len(T):
    print('UNRESTORABLE')
    exit()
ans = 'z' * 51
for i in range(len(S) - len(T) + 1):
    s = S[i:i+len(T)]
    for a,b in zip(s,T):
        if a == b or a == '?':
            continue
        break
    else:
        cand = S[:i] + T + S[i+len(T):]
        #print(cand)
        ans = min(ans, cand.replace('?', 'a'))
print('UNRESTORABLE' if ans == 'z' * 51 else ans)


Fixed submission:
#
# Written by NoKnowledgeGG @YlePhan
# ('ω')
#
#import math
#mod = 10**9+7
#import itertools
#import fractions
#import numpy as np
#mod = 10**4 + 7
"""def kiri(n,m):
  r_ = n / m
  if (r_ - (n // m)) > 0:
    return (n//m) + 1
  else:
    return (n//m)"""

""" n! mod m 階乗
mod = 1e9 + 7
N = 10000000
fac = [0] * N
def ini():
  fac[0] = 1 % mod
  for i in range(1,N):
    fac[i] = fac[i-1] * i % mod"""

"""mod = 1e9+7
N = 10000000
pw = [0] * N
def ini(c):
  pw[0] = 1 % mod
  for i in range(1,N):
    pw[i] = pw[i-1] * c % mod"""

"""
def YEILD():
  yield 'one'
  yield 'two'
  yield 'three'
generator = YEILD()
print(next(generator))
print(next(generator))
print(next(generator))
"""
"""def gcd_(a,b):
  if b == 0:#結局はc,0の最大公約数はcなのに
    return a
  return gcd_(a,a % b) # a = p * b + q"""
"""def extgcd(a,b,x,y):
  d = a
  if b!=0:
    d = extgcd(b,a%b,y,x)
    y -= (a//b) * x
    print(x,y)
  else:
    x = 1
    y = 0
  return d"""
# 最大公約数 と 最小公倍数
"""def gcd(a,b):
  if b == 0:
    return a
  return gcd(b, a % b)
def lcm(a,b):
  g = gcd(a,b)
  return (a * b) // g"""

def readInts():
  return list(map(int,input().split()))
mod = 10**9 + 7

def main():
  import re
  #?tc????
  S = input().replace('?','.')
  T = input()
  #print(S)
  #.tc....
  #print(T)
  #coder
  # print(len(S) - len(T)) 7:5
  # 2
  for i in range(len(S) - len(T), -1,-1):
    # print(re.match(S[i:i+len(T)],T))
    # <_sre.SRE_Match object; span=(0, 5), match='coder'>
    # 後ろから、len(T)文まで見て、そこにTが入るかを検証
    # 入るなら Trueがかえる？
    if re.match(S[i:i+len(T)],T):
      #print(S) 
      S = S.replace('.','a')
      # すべてをaに置き換える(辞書順最初)
      print(S[:i] + T + S[i+len(T):])
      # i-1番目までSの部分、iからi+len(T)-1まではTを入れ（入れれることが確認できたから)
      # そして、i+len(T)番目から最後までSの部分を入れる
      exit()
  print('UNRESTORABLE')
if __name__ == '__main__':
  main()