#include <cstdio>

#include <cstring>

#include <iostream>

using namespace std;

const int MAX_N = ;

const int MAX_M =  + ;

int fa[MAX_N], show[MAX_N];

int in[MAX_N], out[MAX_N];

int set_visited[MAX_N];

char str[MAX_M];

void Init()

{

    for (int i = ; i < MAX_N; ++i)

        fa[i] = i;

    memset(in, , sizeof(in));

    memset(out, , sizeof(out));

    memset(show, , sizeof(show));

    memset(set_visited, , sizeof(set_visited));

}

int Find(int a)

{

    if (fa[a] == a)

        return a;

    else

        return fa[a] = Find(fa[a]);

}

int Union(int a, int b)

{

    int fa_a = Find(a);

    int fa_b = Find(b);

    if (fa_a == fa_b)

        return -;

    if (fa_a > fa_b)

        fa[fa_b] = fa_a;

    else

        fa[fa_a] = fa_b;

    return ;

}

int main()

{

    int case_times, n, len;

    scanf("%d", &case_times);

    while (case_times--)

    {

        scanf("%d", &n);

        Init();

        for (int i = ; i < n; ++i)

        {

            int l, r;

            scanf("%s", str);

            len = strlen(str);

            l = str[] - 'a';

            r = str[len - ] - 'a';

            in[l]++;

            out[r]++;

            show[l] = show[r] = ;

            Union(l, r);

        }

        int set_count = ;

        int not_equal = ;

        int in_big_out = , out_big_in = ;

        bool ok = true;

        for (int i = ; i < MAX_N; ++i)

        {

            if (show[i])

            {

                int fa_i = Find(i);

                if (set_visited[fa_i] == )

                {

                    set_count++;

                    set_visited[fa_i] = ;

                }

                if (set_count > )

                {

                    ok = false;

                    break;

                }

                if (in[i] != out[i])

                    not_equal++;

                if (in[i] == out[i] + )

                    in_big_out++;

                if (in[i] +  == out[i])

                    out_big_in++;

            }

        }

        if (!((not_equal == ) || (out_big_in ==  && in_big_out ==

            && in_big_out + out_big_in == not_equal)))

            ok = false;

        if (ok)

            printf("Ordering is possible.\n");

        else

            printf("The door cannot be opened.\n");

    }

    return ;

}