#include<iostream>

#include<cstdio>

#include<cstring>

#include<string>

#include<algorithm>

#include<queue>

using namespace std;

struct node{

    int num;

    node *lef;

    node *rig;

};

const int maxn=1e3+;

string str[maxn];

int cur;

node *work(){

    node *rt=(node *)malloc(sizeof(node));

    rt->num=str[cur-][]-'A';

    rt->lef=NULL;

    rt->rig=NULL;

    for(int i=cur-;i>=;i--){

        int len=str[i].length();

        for(int j=;j<len;j++){

            node *now=rt;

            while(){

                if(str[i][j]-'A'<now->num){

                    if(now->lef) now=now->lef;

                    else{

                        node *nd=(node *)malloc(sizeof(node));

                        nd->num=str[i][j]-'A';

                        nd->lef=NULL;

                        nd->rig=NULL;

                        now->lef=nd;

                        break;

                    }

                }else{

                    if(now->rig) now=now->rig;

                    else{

                        node *nd=(node *)malloc(sizeof(node));

                        nd->num=str[i][j]-'A';

                        nd->lef=NULL;

                        nd->rig=NULL;

                        now->rig=nd;

                        break;

                    }

                }

            }

        }

    }

    return rt;

}

void preorder(node *rt){

    if(rt==NULL) return;

    printf("%c",rt->num+'A');

    preorder(rt->lef);

    preorder(rt->rig);

    free(rt);

}

int main(){

    cur=;

    while(cin>>str[cur]){

        if(str[cur][]=='*'||str[cur][]=='$'){

            node *rt=work();

            preorder(rt);

            puts("");

            if(str[cur][]=='$') break;

            else cur=;

        }else{

            cur++;

        }

    }

    return ;

}