#include<iostream>
#include<string>
#include<algorithm>
#include<functional>
#include<vector>
#include<set>
#include<queue>
#include<list>
#include<stdio.h>
#include<stdlib.h>

using namespace std;

int main() {
	string s;
	cin >> s;

	int kisyutu[13] = {};

	for (int i = 0; i < 13; ++i) {
		++kisyutu[s[i]-'a'];
	}

	int zero = -1;
	int two = 0;

	int sum = 0;
	for (int i = 0; i < s.length(); ++i) {
		if (kisyutu[i] == 0) {
			zero = i;
		}
		else if (kisyutu[i] == 2) {
			++two;
		}

		sum += kisyutu[i];
	}

	char ans;
	if (sum == 13 && two == 1) {
		ans= zero + 'a';
		cout << ans << endl;
	}
	else if (sum == 13 && two == 0) {

		for (int i = 0; i < s.length(); ++i) {
			ans = i + 'a';
			cout << ans << endl;
		}
		
	}
	else {
		cout << "Impossible" << endl;
	}

}