import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        char[] arr = sc.next().toCharArray();
        int[] counts = new int[13];
        for (char c : arr) {
            counts[c - 'a']++;
        }
        boolean has2 = false;
        char ans = 'c';
        for (int i = 0; i < 13; i++) {
            if (counts[i] > 2 || (counts[i] == 2 && has2)) {
                System.out.println("Impossible");
                return;
            } else if (counts[i] == 2) {
                has2 = true;
            } else if (counts[i] == 0) {
                ans = (char)(i + 'a');
            }
        }
        if (has2) {
            System.out.println(ans);
        } else {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < 13; i++) {
                sb.append((char)(i + 'a')).append("\n");
            }
            System.out.print(sb);
        }
    }
}