#include <iostream>
#include <stdio.h>
#include <cstring>
#include <math.h>
#include <algorithm>
#include <vector>
#include <string>
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define ll long long
#define LL long long
#define mass 1000000007
using namespace std;
int keta(int n,int k){return (n/int(pow(10,double(k-1)))) % 10;} //nの下からk桁目



int main(){

	char a[13];
	rep(i,13){
		cin>>a[i];
	}
	int b[13];
	rep(i,13){
		b[i]=0;
	}
	rep(i,13){
		if(int(a[i])>109){
			cout<<"Impossible"<<endl;
			return 0;
		}
		b[ int(a[i])-97 ]++;
	}
	rep(i,13){
		if(b[i]==0){
			cout<<char(i+97)<<endl;
			return 0;
		}else if(b[i]>1){
			cout<<"Impossible"<<endl;
			return 0;
		}
	}
	rep(i,13){
		cout<<char(i+97)<<endl;
	}
	return 0;
}