#include <cstdio>
#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
#include <utility>
#include <memory.h>

using namespace std;

#define NR_CHILDS 10
#define NR_NODES 100000

struct trie_node_t {
    trie_node_t * childs[10];
    bool is_ending;
};

trie_node_t nodes[NR_NODES];
trie_node_t *trie_root, *node_ending;

void
init_trie(void)
{
    memset(nodes, 0, sizeof(nodes));
    trie_root = nodes;
    node_ending = trie_root + 1;

    return;
}

bool
confict_exists(trie_node_t *root_node)
{
    bool parent_ending(root_node->is_ending);

    for (trie_node_t **iter = root_node->childs, **iter_end = root_node->childs + NR_CHILDS; iter != iter_end; ++iter) {
        if (*iter) {
            if (parent_ending) {
                return true;
            }
            if (confict_exists(*iter)) {
                return true;
            }
        }
    }

    return false;
}

void
add_string(char* str)
{
    trie_node_t *cur(trie_root);
    int c;

    --str;

    while (*++str) {
        if (!cur->childs[c = *str - '0']) {
            cur->childs[c] = node_ending++;
        }
        cur = cur->childs[c];
    }

    cur->is_ending = true;

    return;
}

void
solve_prob(void)
{
    int nr_number;
    char number[11];

    init_trie();

    cin >> nr_number;
    while (nr_number--) {
        cin >> number;
        add_string(number);
    }

    cout << (confict_exists(trie_root) ? "NO" : "YES") << endl;

    return;
}

int
main(void)
{
    int nr_cases;

    ios::sync_with_stdio(false);

    //freopen("test.txt", "r", stdin);

    cin >> nr_cases;
    while (nr_cases--) {
        solve_prob();
    }

    return 0;
}