#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)
#define SZ(n) (int)(n).size()
#define ALL(n) (n).begin(), (n).end()
#define MOD % 1000000007
using namespace std;
typedef long long LL;
typedef vector<int> VI;


int main() {
	string s;
	cin >> s;
	set<char> st;
	REP(i, 13) {
		st.insert(s[i]);
	}
	sort(ALL(s), greater<char>());
	if (s[0] > 'm' || st.size() < 12) {
		cout << "Impossible" << endl;
	} 
	else if (st.size() == 12) {
		REP(i, 13) {
			if (st.find('a' + i) == st.end()) cout << char('a' + i) << endl;
		}
	}
	else {
		REP(i, 13) {
			cout << char('a' + i) << endl;
		}
	}
	return 0;
}