#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int counter[1000];

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

    string S;
    std::cin >> S;

    for(auto& c : S){
        ++counter[(int)c];
    }

    bool flag = true;
    for(int i='a';i<='m';++i){
        if(counter[i] == 0){
            flag = false;
        }
    }

    if(flag){
        for(int i='a';i<='m';++i){
            std::cout << ((char)i) << std::endl;
        }
        return 0;
    }

    int two = -1, zero = -1;
    flag = true;
    for(int i='a';i<='m';++i){
        if(counter[i] == 0){
            if(zero != -1){flag = false;}
            zero = i;
        }else if(counter[i] == 2){
            if(two != -1){flag = false;}
            two = i;
        }
    }

    if(flag && two != -1 && zero != -1){
        std::cout << ((char)zero) << std::endl;
        return 0;
    }

    std::cout << "Impossible" << std::endl;
}