//#include<iostream>
//#include<cstring>
#include<bits/stdc++.h>

using namespace std;
map<string,int> a,b;//1.map的用法

void solve()
{
    a.clear(),b.clear();//2.清除
    int n;string s;
    bool st=0;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        cin>>s;
        string p(s),q(s);//3.让定义字符串内容为s
        q.erase(0,1);//4.删除从0开始的第1个元素   *** q.pop_back()删除最后一个
        //q.erase(1); cout<<q<<' ';
        
        reverse(p.begin(),p.end());//5.翻转
        reverse(q.begin(),q.end());
        //if(a[p]||a[q]||b[q]) st=1;
        if(a[p]||a[q]||b[p]) st=1;
        a[s]=1;
        if(s.front()==s.back()||s.size()==1) st=1;//6.front back begin end
        
        s.erase(s.size()-1,1);
        //s.erase(s.size()-1); cout<<s<<endl;
        
        b[s]=1;
        s.clear();
    }
    
    if(st) printf("YES\n");
    else printf("NO\n");
}

int main()
{
    int t;
    scanf("%d",&t);
    while(t--) solve();
    
    return 0;
}