graph-3

#include<iostream>
#include<string>
#include<list>
#include<queue>

bool BFS(std::list<int>*adj,int n,int s,int d){
    int count=0;
    std::queue<int>q;
    q.push(s);
    bool visited[26][26];
   // visited[s][d]=true;
    while(!q.empty()){
        int v = q.front();
        for (auto i = adj[v].begin(); i != adj[v].end(); ++i) 
        {
          if(!visited[v][*i]){
            q.push(*i);
            count++;
            visited[v][*i]=true;
          }
        }
        q.pop();
    }
    //std::cout<<count<<"\n";
    if(count==n)
    return true;
    
    return false;
}

void DFS(list<int>*adj,int s,bool visited[],string &res){
    visited[s]=true;
    for(auto it=adj[s].begin();it!=adj[s].end();++it){
        if(!visited[*it])
        DFS(adj,*it,visited,res);
    }
    res.push_back(s+'a');
}

string topoSort(list<int>*adj,int N,int k,int s){
    bool visited[N]={false};
    std::string res="";
    DFS(adj,s,visited,res);
    std::reverse(res.begin(),res.end());
    return res;
}

int min(int x, int y) 
{ 
    return (x < y)? x : y; 
} 

string findOrder(string dict[], int N, int K) {
   list<int>*adj=new list<int>[N];
   for(int i=0;i<N-1;++i){
       string word1 = dict[i], word2 = dict[i+1]; 
        for (int j = 0; j < min(word1.length(), word2.length()); j++) 
        { 
            if (word1[j] != word2[j]) 
            { 
                int s = word1[j]-'a';
                int e = word2[j]-'a';
                adj[s].push_back(e);
                break; 
            } 
        } 
      
   }

   return topoSort(adj,N,K,dict[0][0]-'a');
}

int main()
{
	int T;
	std::cin>>T;
	while(T--){
	    int n;
	    std::cin>>n;
	    std::string str[n];
	    for(int i=0;i<n;++i)
	    std::cin>>str[i];
	    std::list<int>*adj = new std::list<int>[26];
	    
	    for(int i=0;i<n;++i){
	        int l = str[i].size()-1;
	        adj[str[i][0]-'a'].push_back(str[i][l]-'a');
	    }
	    
	    if(n==1 && str[0].size()>1)
	        std::cout<<"0\n";
	    else if(n==1 && str[0].size()==1)
	        std::cout<<"1\n";
	    else
	        std::cout<<BFS(adj,n,str[0][0]-'a',str[0][str[0].size()-1]-'a')<<"\n";
	}
	
}