#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; }