S = input()
a = [v for v in S]
a.sort()
s = {v for v in S}
a_m = {chr(i) for i in range(97,110)}
if s == a_m:
    for i in a:
        print(i)
elif len(s) == 12 and s <= a_m:
    b = a_m - s
    for v in b:
        print(v)
else:
    print('Impossible')