import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String S = sc.next();
        int [] alp = new int [26];
        for(int i=0; i<13; i++){
            alp[(S.charAt(i)-'a')]++;
        }
        int z=0;
        for(int i=0; i<13; i++){
            if(alp[i]==0)z++;
        }
        if(z>=2){
            System.out.println("Impossible");
        }else if(z==1){
            for(int i=0; i<13; i++){
                if(alp[i]==0)System.out.println((char)(i+'a'));
            }
        }else{
            for(int i=0; i<13; i++){
                System.out.println((char)(i+'a'));
            }
        }
    }
}