#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    vector<int> a(26);
    REP(i, 13) {
        char c;
        cin >> c;
        a[c - 'a']++;
    }

    int cnt0 = 0, cnt1 = 0, cnt2 = 0, empty;
    REP(i, 13) {
        switch (a[i]) {
            case 0:
                cnt0++;
                empty = i;
                break;
            case 1:
                cnt1++;
                break;
            case 2:
                cnt2++;
                break;
            default:
                break;
        }
    }

    if (cnt1 == 13) {
        REP(i, 13) cout << (char) ('a' + i) << endl;
    } else if (cnt0 == 1 && cnt1 == 11 && cnt2 == 1) {
        cout << (char) ('a' + empty) << endl;
    } else {
        cout << "Impossible" << endl;
    }
    return 0;
}