#include<bits/stdc++.h>
using namespace std;

#define DEBUG(x) cout<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cout<<#v<<":";for(int i=0;i<v.size();i++) cout<<" "<<v[i]; cout<<endl

typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
const int inf=1000000001;
const ll INF=1e16;
#define MOD 1000000007
#define mod 1000000009
#define pi 3.14159265358979323846
#define Sp(p) cout<<setprecision(15)<<fixed<<p<<endl;
int dx[4]={1,0,-1,0}, dy[4]={0,1,0,-1};


int main(){
	int i,j;
	string s;
	cin>>s;
	sort(s.begin(),s.end());
	string t="abcdefghijklmn";
	int flag = 1;
	for(i=0;i<13;i++){
		if(s[i] < 'a' && s[i] > 'm'){
			cout<<"Impossible"<<endl;
			return 0;
		}
		if(i){
			if(s[i-1] == s[i]){
				flag--;
			}
		}
	}
	if(flag == 1){
		for(i=0;i<13;i++){
			cout<<t[i]<<endl;
		}
	}else if(flag < 0){
		cout<<"Impossible"<<endl;
	}else{
		for(i=0;i<13;i++){
			if(s[i]!=t[i]){
				cout<<t[i]<<endl;
				return 0;
			}
		}
	}
}