#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<math.h>
#include<iomanip>
#include<set>
#include<numeric>
#include<cstring>
#include<cstdio>
#include<functional>
#include<bitset>
#include<limits.h>
#include<cassert>
#include<iterator>
#include<complex>
#include<stack>
#include<sstream>
#include<iterator>
using namespace std;
typedef  long long int lint;
typedef pair<int, int> IP;
typedef pair<lint, lint> LLP;
typedef pair<char, char>CP;
#define rep(i, n) for (int i = 0; i < n; i++)
#define repr(i, n) for (int i = n; i >= 0; i--)
#define sort(v) sort((v).begin(), (v).end())
#define reverse(v) reverse((v).begin(), (v).end())
#define upper(v,hoge) upper_bound(v.begin(),v.end(),hoge)
#define lower(v,hoge) lower_bound(v.begin(),v.end(),hoge)
#define llower(v,hoge) *lower_bound(v.begin(), v.end(), hoge)
#define lupper(v,hoge) *upper_bound(v.begin(), v.end(), hoge)

int main() {
	string S;
	cin >> S;
	int N = 13;
	vector<int>A(N);
	int Z = S.size();
	rep(i, Z) {
		A[S[i] - 'a']++;
	}
	int c0 = 0, c1 = 0, c2 = 0;
	rep(i, N) {
		if (A[i] == 0) {
			c0++;
		}
		if (A[i] == 1) {
			c1++;
		}
		if (A[i] == 2) {
			c2++;
		}
	}
	if (c0 == 1 && c1 == 11 && c2 == 1) {
		rep(i, N) {
			if (A[i] == 0) {
				cout << char('a' + i) << endl;
			}
		}
	}
	else if (c1 == 13) {
		cout << 'a' << endl;
		cout << 'b' << endl;
		cout << 'c' << endl;
		cout << 'd' << endl;
		cout << 'e' << endl;
		cout << 'f' << endl;
		cout << 'g' << endl;
		cout << 'h' << endl;
		cout << 'i' << endl;
		cout << 'j' << endl;
		cout << 'k' << endl;
		cout << 'l' << endl;
		cout << 'm' << endl;
	}
	else {
		cout << "Impossible" << endl;
	}
}