#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define IOS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>order_set;
typedef pair<int, int>pr;
#define all(i) i.begin() , i.end()
#define ft first
#define sn second
#define pb push_back
#define totalone(mask) __builtin_popcount(mask)
#define chkbit(mask,bit) (mask&(1LL << bit))
// debug section start
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i : x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
// debug section closed
#define en "\n"
#define sum(n) ((1LL*(n)*(n+1))/ 2LL)
#define sqr(n) (1LL*(n)*(n))
#define vag(a,b) ((a + b - 1)/b)
#define MAXN 200010
#define inf 1e6+5
const int mod = 1e9 + 7;
int n;
char first[23];
int ache[23][26];
int mem[26][(1 << 22)][2];
int vis[26][(1 << 22)][2];
int T = 0;
int f(int ch, int mask, int st)
{
if (mask == (1 << n) - 1) {
return !st;
}
int &ret = mem[ch][mask][st];
if (vis[ch][mask][st] == T) {
return ret;
}
vis[ch][mask][st] = T;
ret = !st;
if (st)
{
for (int i = 0; i < n; i++) {
if (first[i] == ch && !chkbit(mask, i)) {
for (int j = 0; j < 26 && !ret; j++) {
if (ache[i][j]) ret |= f(j, mask | (1 << i), !st);
}
}
}
}
else {
for (int i = 0; i < n; i++)
{
if (first[i] == ch && !chkbit(mask, i)) {
for (int j = 0; j < 26 && ret; j++) {
if (ache[i][j]) ret &= f(j, mask | (1 << i), !st);
}
}
}
}
return ret;
}
void solve()
{
cin >> n;
for (int i = 0; i < n; i++)
{
string s;
cin >> s;
first[i] = s[0] - 'a';
memset(ache[i], 0, sizeof(ache[i]));
for (auto c : s)
{
ache[i][c - 'a'] = 1;
}
}
T++;
int win = 0;
for (int i = 0; i < 26; i++)
{
win |= f(i, 0, 1); // f(char, mask, turn);
}
if (win) cout << "YES\n";
else cout << "NO\n";
}
int main()
{
IOS;
ll t;
t = 1;
cin >> t;
int c = 0;
while ( t-- )
{
cout << "Case " << ++c << ": ";
solve();
}
return 0;
}