#include <bits/stdc++.h>

using namespace std;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    const string s0{ "abcdefghijklm" };
    string s;
    cin >> s;

    sort(s.begin(), s.end());

    if (s == s0)
    {
        for (const auto& ss : s)
            cout << ss << "\n";

        return 0;
    }

    string dif1, dif2;
    set_difference(s.begin(), s.end(),
        s0.begin(), s0.end(),
        inserter(dif1, dif1.end()));
    set_difference(s0.begin(), s0.end(),
        s.begin(), s.end(),
        inserter(dif2, dif2.end()));

    string res;
    if (dif1.size() == 1 && dif2.size() == 1)
        res = dif2;
    else
        res = "Impossible";
    cout << res << "\n";

    return 0;
}