import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Array;
import java.util.Arrays;

import static java.lang.System.in;

public class No548 {
    public static void main(String[] args) throws IOException {

        BufferedReader reader = new BufferedReader(new InputStreamReader(in));

        String S = reader.readLine();

        int[] table = new int[13];

        for (int i = 0; i < 13; i++) {
            int characterAsInt = S.charAt(i) - 97;
            if (0 <= characterAsInt && characterAsInt <= 12) {
                table[characterAsInt] += 1;
            }
        }

        if (allOne(table)) {
            for (int i = 0; i < 13; i++) {
                System.out.println((char) (97 + i));
            }
        } else if (one2AndEleven1AndOne0(table)) {
            for (int i = 0; i < 13; i++) {
                if(table[i] == 0) {
                    System.out.println((char) (i + 97));
                }
            }
        } else {
            System.out.println("Impossible");
        }
        
    }

    private static boolean allOne(int[] table) {

        for (int i = 0; i < 13; i++) {
            if (table[i] != 1) {
                return false;
            }
        }
        return true;
    }

    private static boolean one2AndEleven1AndOne0(int[] table) {

        int counterFor2 = 0;
        int counterFor1 = 0;
        int counterFor0 = 0;

        for (int i = 0; i < 13; i++) {
            if (table[i] == 2) {
                counterFor2 += 1;
            } else if (table[i] == 1) {
                counterFor1 += 1;
            } else if (table[i] == 0) {
                counterFor0 += 1;
            }
        }

        return (counterFor2 == 1) && (counterFor1 == 11) && (counterFor0 == 1);
    }
}