package main

import . "fmt"
import . "strings"

func main() {
	var s string
	Scan(&s)
	zero,one := []rune{},[]rune{}
	two := 0
	for ch:='a'; ch<='m'; ch++ {
		switch Count(s, string(ch)) {
			default:
				Println("Impossible")
				return
			case 0:
				zero = append(zero, ch)
			case 1:
				one = append(one, ch)
			case 2:
				two++
		}
	}
	switch {
		default:
			Println("Impossible")
		case two == 1 && len(zero) == 1:
			Println(string(zero))
		case two == 0 && len(zero) == 0:
			for _, ch := range one {
				Println(string(ch))
			}
	}
}