//#include <bits/stdc++.h>
#include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
#include <math.h>
#include <iomanip>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;

#define rep(i,n) for(int i = 0; i < (n); i++)
#define pb push_back 
#define eb emplace_back 
#define all(x) x.begin() , x.end()
#define fi first
#define se second
#define Yes() {puts("YES");return;}
#define No()  {puts("No"); return;}
#define P pair <int , int>
#define vb vector<bool>
#define vi vector<int> 
#define vll vector<ll> 
#define vvi vector<<vector

const int mod = 1000000007;
const ld PI = 3.14159265358979;
const int INF = 1001001001;
const ll LINF = (1LL << 60);
const int MX = 200005;

ll gcd (ll a , ll b) {if (a < b) swap(a , b);if (b == 0) return 1;if (a % b == 0) return b;else return gcd (b , a % b);}
bool is_2power (ll x) { if((x & (x - 1)) == 0) return true; else return false;}

bool is_prime (ll x) {
    if (x == 1) return false;
    if (x == 2 || x == 3 || x == 5 || x == 7) return true;
    if((x & 1) == 0) return false;
    for (ll i = 3; i * i <= x; i += 2) if(x % i == 0)return false;
    return true;
}

void is_prime2() {
    const int sz = 10001; //使う時は外に出す
    vb table(sz , 0); //使う時は外に出す
    for (int i = 2; i < sz; i++) {
        for(int j = 2; i * j <= sz; j++) {
            table[i * j] = true;
        }
    }
}

vector<int> divisor (ll x) {
    vector<int> ret;
    for (int i = 2; i * i <= x; i++) {
        while (x % i == 0) {
            ret.push_back(i);
            x /= i;
        }
    }
    if (x > 1) {
        ret.push_back(x);
    }
    return ret;
}

ll modpow (ll x , ll p , ll m) {
    ll ret = 1;
    while (p > 0) {
        if(p & 1)ret *= x;
        x *= x;
        x %= m;
        p >>= 1;
    }
    return ret;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
    string s;
    cin >> s;
    vi cnt(20 , 0);
    for (auto i : s) {
        cnt[i - 'a']++;
    }
    bool ok1 = true;
    for (int i = 0; i < 13; i++) {
        if (cnt[i] != 1) {
            ok1 = false;
            break;
        }
    }
    if (ok1) {
        for (int i = 0; i < 13; i++) {
            cout << char('a' + i) << endl;
        }
        exit(0);
    }
    int cnt_0 = 1 , cnt_1 = 11 , cnt_2 = 1;
    int id;
    for (int i = 0; i < 13; i++) {
        if (cnt[i] == 0) {
            cnt_0 -= 1;
            id = i;
        } else if (cnt[i] == 1) {
            cnt_1 -= 1;
        } else if (cnt[i] == 2) {
            cnt_2 -= 1;
        }
    }
    if (cnt_0 == 0 && cnt_1 == 0 && cnt_2 == 0) {
        cout << char('a' + id) << endl;
        exit(0);
    }
    cout << "Impossible" << endl;
    return 0;
}