#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<iostream>
#include<vector>
using namespace std;
int n,vis[1005],len[1005],k,in[1005],out[1005],ans[1005],cnt;
string s[1005];
struct node{
    int u,m;
};
vector<node> g[1005];
void euler(int x){
    for(int i=0;i<g[x].size();i++){
        int v=g[x][i].u;
        if(!vis[ g[x][i].m ]){
            vis[ g[x][i].m ]=1;
            euler(v);
            cnt++;
            ans[cnt]=g[x][i].m;
        }
    }
}
int main(){
    int t; scanf("%d",&t);
    while(t--){
        int start=100;
        cin >> n;
        k=0;
        memset(vis,0,sizeof(vis));
        memset(in,0,sizeof(in));
        memset(out,0,sizeof(out));
        for(int i=1;i<=26;i++) g[i].clear();
        for(int i=1;i<=n;i++){
            cin >> s[i];
        }
        sort(s+1,s+n+1);
        for(int i=1;i<=n;i++){
            len[i]=s[i].size();
        }
        for(int i=1;i<=n;i++){
            node t;
            t.u=s[i][len[i]-1]-‘a‘+1; t.m=i;
            g[ s[i][0]-‘a‘+1 ].push_back( t );
            out[ s[i][0]-‘a‘+1 ]++; in[s[i][len[i]-1]-‘a‘+1]++;
            start=min(start,s[i][0]-‘a‘+1);
            start=min(start,s[i][len[i]-1]-‘a‘+1);
        }
        int fin=0,fout=0,end=0,flag=0;
        for(int i=1;i<=26;i++){
            if(in[i]+1==out[i]){
                start=i; fin++;
            }
            else if(in[i]==out[i]+1){
                fout++;
            }
            else if(in[i]!=out[i]) flag=1;
        }
        if(flag==1) { printf("***\n"); continue; }
        else if( (fin==1&&fout==1) || (fin==0&&fout==0) ) {
            cnt=0;
            euler(start);
            if(cnt==n){
                for(int i=cnt;i>=1;i--) {
                    if(i==cnt) cout << s[ ans[i] ];
                    else cout << "." << s[ ans[i] ];
                }
                printf("\n");
            }
            else { printf("***\n"); continue; }
        }
        else { printf("***\n"); continue; }
    }

    return 0;
}