#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <iomanip>
#include <math.h> 
#include <stack>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <tuple>
#include <cctype>
#include <ctype.h>
#include <set>
#include <sstream>

using namespace std;



int main() {
	int i, j, k;
	string s;
	vector<int>list(13, 0);

	cin >> s;

	for (i = 0; i < s.length(); i++) {
		if (s[i] - 97 >= 13) {
			cout << "Impossible" << endl;
			return 0;
		}
		list[(int)s[i] - 97]++;
	}

	int one = 0, two = 0, th = 0;

	for (i = 0; i < 13; i++) {
		if (list[i] == 1) {
			one++;
		}
		else if (list[i] == 2) {
			two++;
		}
		else if (list[i] >= 3) {
			th++;
		}
	}

	if (th >= 1 || two >= 2) {
		cout << "Impossible" << endl;
		//return 0;
	}
	else if (one == 13) {
		for (i = 0; i < 13; i++) {
			cout << (char)('a' + i ) << endl;
		}
	}
	else if (one == 11 && two == 1) {
		for (i = 0; i < 13; i++) {
			if (list[i] == 0) {
				char ch = 'a';
				cout << (char)(ch + i) << endl;
				break;
			}
		}
	}





	getchar();
	getchar();
	return 0;
}