#include<iostream>
#include<vector>
#include<algorithm>
#include<cctype>
#include<utility>
#include<string>
#include<cstring>
#include<cmath>
#include<numeric>
#include<queue>
#include<climits>
#include<cstdio>


#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define llong long long
#define pb(a) push_back(a)
//#define INF ((LLONG_MAX) / (2))
using namespace std;
typedef pair<int, int> P;
typedef pair<llong, llong> LP;
typedef pair<int, P> PP;
typedef pair<llong, LP> LPP;
typedef long long int ll;
typedef pair<ll,int> LL_IP;
typedef pair<ll,ll> LL_LLP;
#define INF 1e9+7


int main(){

    string str = "abcdefghijklm";
    string s;
    cin >> s;

    vector<int> arr(26,0);
    REP(i,s.length()){
        arr[s[i]-'a']++;
    }
    int one = 0,two = 0;
    
    REP(i,13){
        if(arr[i] == 1){
            one++;
        }
        if(arr[i] == 2){
            two++;
        }
    }

    if(one == 13 && two == 0){
        REP(i,str.length()){
            cout << str[i] << endl;
        }
    }else if(one == 11 && two == 1){
        REP(i,13){
            if(arr[i] == 0){
                cout << str[i] << endl;
                break;
            }
        }
    }else{
        cout << "Impossible" << endl;
    }



    return 0;
}