#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using VI = vector<int>;
using VL = vector<int>;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define allpt(v) (v).begin(), (v).end()

const int mod = 1e9 + 7;
const string wsp = " ";
const string tb = "\t";
const string rt = "\n";

template <typename T>
void show1dvec(vector<T> v)
{
    int n = v.size() - 1;
    rep(i, n) cout << v[i] << wsp;
    cout << v[n] << rt;
    return;
}

int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    VI w(13, 0);
    string s;
    cin >> s;
    rep(i, 13) w[s[i] - 'a']++;

    if (count(allpt(w), 1) == 13) rep(i, 13) cout << (char) ('a' + i) << rt;
    else if (count(allpt(w), 0) == 1 && count(allpt(w), 1) == 11 && count(allpt(w), 2) == 1) rep(i, 13) {if (w[i] == 0) cout << (char) ('a' + i) << rt;}
    else cout << "Impossible" << rt;
    return 0;
}