def is_replaceable(s, t):
    if len(s) < len(t):
        return 'UNRESTORABLE'

    for i in range(len(s) - len(t) + 1):

        replaceable = True
        for x,y in zip(s[i:], t):
            if x != y and x != '?':
                replaceable = False

        if replaceable:
            s = s[:i] + t + s[i + len(t):]
            return s.replace('?', 'a')

    return 'UNRESTORABLE'


s, t = input(), input()
print(is_replaceable(s, t))