#include <bits/stdc++.h>
using namespace std;

int main() {
    string s;
    cin >> s;
    vector<int> v(13);
    vector<int> v1(13, 1);
    vector<int> v2(13, 1);
    v2[0] = 0;
    v2[12] = 2;
    for(int i=0;i<13;i++) {
        int c = s[i] - 'a';
        v[c]++;
    }
    vector<int> vv = v;
    sort(vv.begin(), vv.end());
    if(vv == v1) {
        for(int i=0;i<13;i++) {
            cout << (char)('a' + i) << endl;
        }
    }
    else if(vv == v2) {
        char c = 'a';
        for(int i=0;i<13;i++) {
            if(v[i] == 0) {
                c += i;
            }
        }

        cout << c << endl;
    }
    else cout << "Impossible" << endl;

    return 0;
}