#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>

typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;

ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;
    return gcd(b, a % b);
}
int lcm(int a, int b) {
    return a * b / gcd(a, b);
}

long long mod_exp(long long b, long long e, long long m) {
    if (e > 0 && b == 0) return 0;
    long long ans = 1;
    b %= m;

    while (e > 0) {
        if ((e & 1LL)) ans = (ans * b) % m;
        e = e >> 1LL;
        b = (b * b) % m;
    }

    return ans;
}


int main()
{

    int Q;
    Q = 1;
    //cin >> Q;
    
    while (Q--) {
        string p;
        cin >> p;
        string a = "abcdefghijklm";
        map<char, int>mp;
        if(p.size())

        
        int z = 0; int t = 0;
        vector<char>c;
        if (p.size() != 13) {
            cout << "Impossible";
            return 0;
        }
        for (int i = 0; i < a.size(); i++) {
            
                string r = p;
                r.push_back(a[i]);
                set<char>s;
                bool f = 0;
                for (int k = 0; k < r.size(); k++) {
                    mp[r[k]]++;
                    if (r[k] > 'm')f = 1;
                    s.insert(r[k]);
                }
                if (f)continue;
                if (s.size() == 13)c.push_back(a[i]);
                
                
            
        }
        if (c.size()) {
            for (int i = 0; i < c.size(); i++)cout << c[i] << endl;
        }
        else cout << "Impossible";
    }
    return 0;
}