#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=100000+10;
int trie[maxn][20];
char c[maxn][20];
int tot;
bool endi[maxn*20];
void myinsert(char* st){
int len=strlen(st);
int ch,p=1;
for (int i=0;i<len;i++){
ch=st[i]-'0'+1;
if(!trie[p][ch]) trie[p][ch]=++tot;
p=trie[p][ch];
}
endi[p]=true;
}
bool findi(char* st){
int len=strlen(st);
int p=1;
for (int i=0;i<len;i++){
p=trie[p][st[i]-'0'+1];
if(p==0) return true;
if(endi[p]&&i!=len-1) return false;
}
return true;
}
int main(){
int t,n;
bool ans;
scanf("%d",&t);
while(t--){
tot=1;
memset(endi,0,sizeof(endi));
memset(trie,0,sizeof(trie));
memset(c,'0',sizeof(c));
ans=true;
scanf("%d",&n);
for (int i=1;i<=n;i++){
scanf("%s",c[i]);
myinsert(c[i]);
}
for (int i=1;i<=n;i++){
if(!findi(c[i])) {
printf("NO\n");
ans=false;
break;
}
}
if(ans) printf("YES\n");
}
return 0;
}