#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>

int main(void) {

	//std::ifstream inf("Text.txt");	std::cin.rdbuf(inf.rdbuf());

	std::string S;
	std::cin >> S;

	std::vector<int> A(13);
	for (unsigned int i = 0; i < S.length(); i++) {
		if (S[i] >= 'n') {
			std::cout << "Impossible" << std::endl;
			return 0;
		}
		A[S[i] - 'a']++;
	}


	int cnt = std::count(A.begin(), A.end(), 1);
	if (cnt == 13) {
		for (int i = 0; i < 13; i++) {
			std::cout << static_cast<char>('a' + i) << std::endl;
		}
	}
	else if (cnt == 11) {
		for (int i = 0; i < 13; i++) {
			if (A[i] == 0) {
				std::cout << static_cast<char>('a' + i) << std::endl;
			}
		}
	}
	else {
		std::cout << "Impossible" << std::endl;
	}

	return 0;
}