func main()
	var s: []char :: cui@input()
	do s.sort()
	if(s = "abcdefghijklm")
		for i(0, 12)
			do cui@print("\{s[i]}\n")
		end for
		ret
	end if
	
	var cnt: dict<char, int> :: #dict<char, int>
	for i(0, 12)
		var c: char :: s[i]
		do cnt.add(c, cnt.get(c, &) + 1)
	end for
	if(^cnt <> 12)
		do cui@print("Impossible\n")
	else
		for i(0, 12)
			var c: char :: 'a'.offset(i)
			if(!cnt.exist(c))
				do cui@print("\{c}\n")
			end if
		end for
	end if
end func