/*
 Author                             :     unlucky_13
 Problem_link                       :     http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=156&problem=136&mosmsg=Submission+received+with+ID+11792907
 Category                           :
 Algorithm_Used                     :
 */

#include<cstdio>
#include<sstream>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<algorithm>
#include<set>
#include<queue>
#include<stack>
#include<list>
#include<iostream>
#include<fstream>
#include<numeric>
#include<string>
#include<vector>
#include<cstring>
#include<map>
#include<iterator>
#define LL long long int
//const long long int inf = 2147483647 ;
//const int minx=;
//const int maxn=;

using namespace std;
int M[50][50] ;
vector<char>ans ;
int taken[100] ;


void DFS(int u)
{

    for(int i=0;i<31;i++)
    {
        if(M[u][i]==1 && taken[i]==0) DFS(i) ;
    }
    ans.push_back(u+'A') ;
    taken[u]=1 ;
    return ;

}




int main() {

    freopen("C:\\Users\\Mazhar\\Desktop\\Text_Files\\in.txt", "r", stdin);

    char in[5000][25] ;
    int I ;
    while(scanf("%s",in[0])!=EOF)
    {
        memset(M,0,sizeof(M)) ;
        ans.clear() ;
        for(int i=0;i<31;i++) taken[i]=1 ;
        I=1 ;
        while(1)
        {
            scanf("%s",in[I]) ;
            if(in[I][0]=='#') break ;
            else
            {

                for(int j=0;j<strlen(in[I]);j++) taken[in[I][j]-'A']=0 ;
                I++ ;
            }
        }

        for(int i=0;i<I-1;i++){
            for(int j=i+1;j<I;j++){
                int k = 0 ;
                while(in[i][k]==in[j][k]) k++ ;
                if(in[i][j]!='\0' ||in[j][k]!='\0')
                {
                  M[in[j][k]-'A'][in[i][k]-'A']=1 ;
                }
            }
        }


        for(int i=0;i<31;i++){
             if(taken[i]==0) DFS(i) ;
        }
        for(int i=0;i<ans.size();i++) cout<<ans[i] ;
        cout<<endl ;


    }








    return 0;

}