import java.io.*;
import java.util.*;


public class Main_yukicoder548 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		char[] s = sc.next().toCharArray();

		int[] cnt = new int[26];
		for (char c : s) {
			cnt[c - 'a']++;
		}

		int sum = 0;
		int zcnt = 0;
		for (int i = 0; i < 13; i++) {
			sum += cnt[i];
			if (cnt[i] == 0) {
				zcnt++;
			}
		}

		if (sum > 13 || zcnt > 1) {
			pr.println("Impossible");
			return;
		}

		if (zcnt == 0) {
			for (int i = 0; i < 13; i++) {
				pr.println((char)(i + 'a'));
			}
		} else {
			for (int i = 0; i < 13; i++) {
				if (cnt[i] == 0) {
					pr.println((char)(i + 'a'));
					break;
				}
			}
		}
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}