2
3
911
97625999
91125426
5
113
12340
123440
12345
98346

NO
YES

#include <cstdio>
#include <cstring>
char s[15];
bool flag;

struct node
{
    node *next[10];
    bool end;
    node()
    {
        memset(next, false, sizeof(next));
        end = false;
    }
};

void Insert(node *p, char *s)
{
    bool f = true;
    for(int i = 0; s[i] != '\0'; i++)
    {
        int idx = s[i] - '0';
        if(p -> next[idx] == NULL)
        {
            p -> next[idx] = new node();
            f = false;
        }
        p = p -> next[idx];
    }
    p -> end = true;
    if(f)
        flag = true;
}

void Search(node *p, char *s)
{   
    for(int i = 0; s[i] != '\0'; i++)
    {
        int idx = s[i] - '0';
        if(p -> end)
        {
            flag = true;
            return;
        }
        if(p -> next[idx] != NULL)
            p = p -> next[idx];
    }
}

void Delete(node *p)
{
    for(int i = 0; i < 10; i++)
        if(p -> next[i]) 
            Delete(p -> next[i]);
    delete p;
}

int main()
{
    int T, n;
    scanf("%d", &T);
    while(T--)
    {
        flag = false;
        node *root = new node();
        scanf("%d", &n);
        for(int i = 0; i < n; i++)
        {
            scanf("%s", s);
            Insert(root, s);
            if(!flag)
                Search(root, s);
        }
        printf("%s\n", flag ? "NO" : "YES");
        Delete(root);
    }
}