#include <iostream>
using namespace std;

int main(){
    string S;
    cin >> S;
    char alphabets[13] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm'};
    int alphabets_have[13];
    for(int i = 0; i < 13; i++){
        alphabets_have[i] = 0;
    }
    for(int i = 0; i < 13; i++){
        for(int j = 0; j < 13; j++){
            if(alphabets[j] == S[i]){
                alphabets_have[j]++;
                break;
            }
        }
    }
    bool have_no = false;
    bool have_2 = false;
    char nothing_alphabet;
    for(int i = 0; i < 13; i++){
        if(!alphabets_have[i]){
            if(!have_no){
                have_no = true;
                nothing_alphabet = alphabets[i];
            }else{
                cout << "Impossible" << endl;
                return 0;
            }
        }else if(alphabets_have[i] == 2){
            have_2 = true;
        }
    }
    if(have_no && have_2){
        cout << nothing_alphabet << endl;
    }else if(!have_no && !have_2){
        for(int i = 0; i < 13; i++){
            cout << alphabets[i] << endl;
        }
    }else{
        cout << "Impossible" << endl;
    }
}