#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;
int main()
{
unsigned long long int pre=0,numl=0,t=0,n=0,i=0,j=0,k=0,index=0;
cin>>t;
while(t--)
{
cin>>n;
string str,start,end;
int flag[n];
for(i=0;i<n;i++)
{
cin>>str;
flag[i]=1;
start=start+str[0];
end=end+str[(str.length()-1)];
}
start=start+'\0';
end=end+'\0';
for(j=0;j<n;j++)
{
index=j;
numl=0;
for(i=0;i<n;i++)
{
flag[i]=1;
}
flag[index]=0;
for(k=0;k<n;k++)
{
i=start.find(end[index]);
if(i!=index && flag[i]!=0)
{
flag[i]=0;
index=i;
numl=numl+1;
}
else if(i==index)
{
i=start.find(end[index],i+1);
if(flag[i]!=0)
{
flag[i]=0;
index=i;
numl=numl+1;
}
else
break;
}
if(numl==(n-1))
break;
}
if(numl==(n-1))
break;
}
if(numl==(n-1))
cout<<"YES"<<endl;
else
cout<<"NO"<<endl;
}
return 0;
}
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