Takahashi is a user of a site that hosts programming contests.   When a user competes in a contest, the _rating_ of the user (not necessarily an integer) changes according to the _performance_ of the user, as follows:    * Let the current rating of the user be a.   * Suppose that the performance of the user in the contest is b.   * Then, the new rating of the user will be the avarage of a and b.  For example, if a user with rating 1 competes in a contest and gives performance 1000, his/her new rating will be 500.5, the average of 1 and 1000.  Takahashi's current rating is R, and he wants his rating to be exactly G after the next contest.   Find the performance required to achieve it.
s = input()
t = input()

res = []

for s_index in range(len(s)-len(t)+1):
    if s[s_index] in ['?', t[0]]:
        s_p = s[s_index:s_index+len(t)]
        if len([True for x in range(len(s_p)) if s_p[x] in ['?', t[x]]]) == len(t):
            res.append(s[:s_index].replace('?', 'a') + t + s[s_index+len(t):].replace('?', 'a'))

if res:
    print(sorted(res)[0])
else:
    print('UNRESTORABLE')

r = int(input())
g = int(input())

print(2*g-r)
