import collections

s = input()

clc_s = collections.Counter(list(s))
key_list = list(clc_s.keys())
value_list = list(clc_s.values())

count1 = value_list.count(1)
count2 = value_list.count(2)

res = []
if count1 == 13 or (count1 == 11 and count2 == 1):
    if count1 == 13:
        for i in range(13):
            res.append(chr(ord('a') + i))
    else:
        for i in range(13):
            cur_char = chr(ord('a') + i)
            if key_list.count(cur_char) == 0:
                res.append(cur_char)
else:
    res.append('Impossible')
    
for i in range(len(res)):
    print(res[i])