#define _USE_MATH_DEFINES
#include<iostream>
#include<vector>
#include<algorithm>
#include<cmath>
#include<string>
#include<iomanip>
#include<numeric>
#include<queue>
#include<deque>
#include<stack>
#include<set>
#include<map>
#include<random>
using namespace std;
typedef long long ll;
const int mod=1e9+7;
int main(){
	string s;
	cin>>s;
	int cnt[13]={};
	for(auto x:s)
		cnt[x-'a']++;
	if(count(cnt,cnt+13,1)==13){
		for(int i=0;i<13;i++)
			cout<<char('a'+i)<<endl;
	}else if(count(cnt,cnt+13,1)==11)
		cout<<char('a'+find(cnt,cnt+13,0)-cnt)<<endl;
	else
		cout<<"Impossible"<<endl;
}