using System;
using System.Collections.Generic;
using System.Linq;

class Program{
    static void Main(){
        new Magatro().Solve();
    }
}

class Magatro{
    private string S = Console.ReadLine();
    private int[] Count = new int[200];
    public void Solve(){
        foreach(var c in S){
            Count[c]++;
        }
        int one = 0;
        int two = 0;
        char cc='a';
        for(char c = 'a';c<='m';c++){
            switch(Count[c]){
                case 0:
                cc = c;
                break;
                case 1:
                one++;
                break;
                case 2:
                two++;
                break;
            }
        }
        if(one==13&&two==0){
            for(char c='a';c<='m';c++){
                Console.WriteLine(c);
            }
        }
        else if(one==11&&two==1){
            Console.WriteLine(cc);
        }
        else{
            Console.WriteLine("Impossible");
        }
    }
}