#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

string solve(const string& s)
{
    vector<int> v(13);
    for(int i=0; i<13; ++i){
        if('a' <= s[i] && s[i] <= 'm')
            ++ v[s[i] - 'a'];
        else
            return "";
    }

    if(count(v.begin(), v.end(), 0) > 1)
        return "";

    auto it = find(v.begin(), v.end(), 0);
    if(it == v.end())
        return "abcdefghijklm";
    else
        return string(1, 'a' + (it - v.begin()));
    
}

int main()
{
    string s;
    cin >> s;

    string ans = solve(s);
    if(ans.empty()){
        cout << "Impossible" << endl;
    }
    else{
        for(char c : ans)
            cout << c << endl;
    }

    return 0;
}