#include <cstdio>#include <cstdlib>#include <cstring>#include <algorithm>#include <cmath>#include <stack>#include <queue>#include <vector>#include <map>#include <string>#include <iostream>using namespace std;const int maxn=2222;int cmp(const string &a,const string &b){    return a<b;}struct Node{    int to;int val;int vis;};string str[maxn];vector<Node> head[maxn];int vis[maxn];int father[100];void add(int from,int to,int val,int vis ){    Node k; k.to=to; k.val=val;k.vis=vis;    head[from].push_back(k);}int getfather(int x){    if(x!=father[x]) father[x]=getfather(father[x]);    return father[x];}void link(int a,int b){    int fa=getfather(a);int fb=getfather(b);    father[fa]=fb;}stack<string >  q;void dfs(int x){    int len=head[x].size();        for(int i=0;i<len;i++){        if(!head[x][i].vis){            //cout<<x<<" "<<head[x][i].to<<endl;            head[x][i].vis=1;            dfs(head[x][i].to);            q.push(str[head[x][i].val]);        }    }}void output(){    string a= q.top(); q.pop();    cout<<a;    while(!q.empty()){        cout<<"."<<q.top();        q.pop();    }}int in[100];int out[100];int main(){    int Icase;    cin>>Icase;    int n;    while(Icase--){        memset(vis,0,sizeof(vis));        for(int i=0;i<26;i++)            father[i]=i;        memset(in,0,sizeof(in));        memset(out,0,sizeof(out));        for(int i=0;i<=maxn;i++)            head[i].clear();        cin>>n;        for(int i=0;i<n;i++)            cin>>str[i];        sort(str,str+n,cmp);        for(int i=0;i<n;i++){            int a=str[i][0]-‘a‘; int len=str[i].size();int b=str[i][len-1]-‘a‘;            add(a,b,i,0); vis[a]=1;vis[b]=1; in[b]++;out[a]++; link(a,b);        }        int ans=0;        for(int i=0;i<26;i++)            if(vis[i]) if(i==father[i]) ans++;        int flag=0;int in1=0;int out1=0;int sign;int sign1;        for(int i=0;i<26;i++)        if(vis[i]) {            sign1=i;break;        }        for(int i=0;i<26;i++)        if(vis[i]){            if(in[i]==out[i]) continue;            if(in[i]-out[i]==1){                in1++;            }            if(out[i]-in[i]==1){                out1++; sign=i;            }            if(out[i]-in[i]>1||out[i]-in[i]>1){                flag=1;break;            }        }        //cout<<sign<<endl;system("pause");        if(!flag) if(in1>1||out1>1) flag=1;        if(ans!=1||flag) cout<<"***"<<endl;        else{            if(in1!=0) dfs(sign);            else dfs(sign1);            output();            cout<<endl;        }    }    return 0;}