# your code goes here
s="abcdefghijklm"
t=gets.chomp
h={}
s.chars{|e|
	s1=s+e
	s1=s1.split("").sort.join("")
	h[s1]=1
}
c=0
s.chars{|e|
	t1=t+e
	t1=t1.split("").sort.join("")
	if h.key?(t1) then
		puts e
		c+=1
	end	
}
puts "Impossible" if c==0