#include<bits/stdc++.h>
using namespace std;
const int L=128;
struct node{
	char c;
	string s;
	node(char c,string s):c(c),s(s){}
	inline bool operator<(const node &o)const{return s<o.s;}
};
vector<node> e[L];
map<pair<int,int>,int> mp;
int n,cnt,ind[L],oud[L],minn='{',beg;
string str,ans;
inline void dfs(int u){
	for(int i=0;i<e[u].size();i++)
		if(mp[make_pair(u,e[u][i].c)]){
			mp[make_pair(u,e[u][i].c)]--;
			ans=ans+e[u][i].s+".";
			cnt++;
			dfs(e[u][i].c);
		}
}
int main(){
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>str;
		e[str[0]].push_back(node(str[str.size()-1],str));
		oud[str[0]]++;ind[str[str.size()-1]]++;
		mp[make_pair(str[0],str[str.size()-1])]++;
		minn=min(minn,(int)min(str[0],str[str.size()-1]));
	}
	for(int i='a';i<='z';i++)sort(e[i].begin(),e[i].end());
	for(int i='a';i<='z';i++){
		if(abs(ind[i]-oud[i])>2){cout<<"***";return 0;}
		if(ind[i]!=oud[i])cnt++;
	}
	if(cnt>2){cout<<"***";return 0;}
	else if(!cnt)beg=minn;
	else for(int i='a';i<='z';i++)
			if(oud[i]-ind[i]==1){beg=i;break;}
	cnt=0;
	dfs(beg);
	if(cnt<n){cout<<"***";return 0;}
	ans.erase(ans.size()-1);
	cout<<ans;
	return 0;
}