#include <bits/stdc++.h>
using namespace std;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0); 
	
	string s;
	cin >> s;
	string t = "abcdefghijklm";
	vector<int> a(13);
	int n = s.size();
	for(int i = 0; i < n; i++) {
		for(int j = 0; j < 13; j++) {
			if(s[i] == t[j]) a[j]++;
		}
	}
	vector<int> b = a;
	sort(b.begin(), b.end());
	if(b[11] >= 2 || b[1] == 0) {
		cout << "Impossible" << endl;
		return 0;
	}
	if(b[12] == 1 && b[0] == 0) {
		cout << "Impossible" << endl;
		return 0;
	}
	for(int i = 0; i < 13; i++) {
		if(a[i] == 0) {
			cout << t[i] << endl;
			return 0;
		}
	}
	for(int i = 0; i < 13; i++) {
		cout << t[i] << endl;
	}
	return 0;
}