#include<iostream>
#include<string>
#include<algorithm>
#define M 1000
using namespace std;
int main()
{
unsigned long long t;
cin>>t;
while(t--)
{
//declaration
char strings[M][2];
int en[26]={0},strt[26]={0};
unsigned long long n,link=0;
string inp;
int flag[26]={0};
int flag2[M]={0};
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>inp;
strings[i-1][0]=inp[0];
strings[i-1][1]=inp[inp.length()-1];
strt[(int)inp[0]-(int)'a']++;
en[(int)inp[inp.length()-1]-(int)'a']++;
}
for(int i=0;i<26;i++)
link+=min(strt[i],en[i]);
//cout<<link<<endl;
for(int i=0;i<n;i++)
{
if(strings[i][0]==strings[i][1] )
{
for(int j=i+1;j<n;j++)
{
if(strings[i][0]==strings[j][0] or strings[i][0]==strings[j][1] )
{
flag[(int)strings[j][0]-(int)'a']=1;
flag[(int)strings[j][1]-(int)'a']=1;
}
}
if(!flag[(int)strings[i][0]-(int)'a'])
{
link--;
//cout<<strings[i][0]<<strings[i][1]<<endl;
flag[(int)strings[i][0]-(int)'a']=1;
}
}
else if(strings[i][0]!=strings[i][1] and !flag2[i])
{
for(int j=i+1;j<n;j++)
{
if(strings[i][0]==strings[j][1] and strings[j][0]==strings[i][1] and !flag2[j] )
{
link--;
//cout<<strings[i][0]<<strings[i][1]<<endl;
//cout<<strings[j][0]<<strings[j][1]<<endl;
flag2[j]=1;
flag[(int)strings[i][0]-(int)'a']=1;
flag[(int)strings[i][1]-(int)'a']=1;
break;
}
}
}
flag2[i]=1;
}
//cout<<link<<endl;
if(link>=n-1)
cout<<"YES"<<endl;
else
cout<<"NO"<<endl;
}
return 0;
}
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