#include<bits/stdc++.h>
#include <atcoder/all>
#ifdef LOCAL
#include <debug_print.hpp>
#define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (static_cast<void>(0))
#endif
using namespace atcoder;
using mint=modint998244353;
using namespace std;
using ll=long long;
using ul=unsigned long long;
int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1};
int dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};
using Graph=vector<vector<int>>;
int op(ll a,ll b){return int(a+b);}
int e(){return 0;}
int main(){
    string S;
    cin>>S;
    vector<bool>A(13);
    for(auto a:S)A[a-'a']=true;
    if(count(A.begin(),A.end(),true)==13){
        for(int i=0;i<13;i++){
            cout<<char(i+'a')<<endl;
        }
    }
    else if(count(A.begin(),A.end(),true)==12){
        for(int i=0;i<13;i++)if(!A[i])cout<<char(i+'a')<<endl;
    }
    else cout<<"Impossible"<<endl;
}