#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <memory>
#include <numeric>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <functional>

#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define MOD 1000000007
#define int long long
using ll = long long;
using namespace std;
const int INF = 1LL << 50;
using P = pair<int, int>;

template <class T>
bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    else {
        return false;
    }
}
template <class T>
bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    else {
        return false;
    }
}
struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(20);
    }
} SETUP;

signed main() {
    string s; cin >> s;
    vector<int> as(26,0);
    for (auto c : s) {
        int i = c - 'a';
        as[i]++;
    }

    for (char c = 'n'; c <= 'z'; c++) {
        if (as[c - 'a'] > 0) {
            puts("Impossible");
            return 0;
        }
    }

    int two = 0;
    int one = 0;
    int zero = 0;
    char zero_c = 'a';
    for(char c = 'a'; c <= 'm'; c++) {
        int idx = c - 'a';
        if (as[idx] > 2) {
            puts("Impossible");
            return 0;
        }
        else if (as[idx] == 2) {
            two++;
        }
        else if (as[idx] == 1) {
            one++;
        }
        else {
            zero++;
            zero_c = c;
        }
    }

    if (one == 13) {
        for (char c = 'a'; c <= 'm'; c++) {
            cout << c << endl;
        }
    }
    else if (two == 1 && zero == 1) {
        cout << zero_c << endl;
    }
    else {
        puts("Impossible");
    }
}