#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define mod 1000000007
#define esp 0.00000000001
const int N=1e5+10,M=1e6+10,inf=1e9;
const ll INF=1e18+10;
int fa[110],du[110],flag[110];
int Find(int x)
{
    return x==fa[x]?x:fa[x]=Find(fa[x]);
}
void update(int u,int v)
{
    int x=Find(u);
    int y=Find(v);
    if(x!=y)
    {
        fa[x]=y;
    }
}
void init()
{
    for(int i=0;i<=30;i++)
        fa[i]=i;
    memset(du,0,sizeof(du));
    memset(flag,0,sizeof(flag));
}
char a[N];
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        init();
        int n,p=-1;
        scanf("%d",&n);
        for(int i=1;i<=n;i++)
        {
            scanf("%s",a);
            int u=a[0]-‘a‘+1;
            int v=a[strlen(a)-1]-‘a‘+1;
            update(u,v);
            du[u]++;
            du[v]--;
            flag[u]++;
            flag[v]++;
        }
        int ans1=0,ans2=0;
        for(int i=1;i<=26;i++)
        {
            if(!flag[i])
                continue;
            if(du[i]==0)
            {
                if(p==-1)
                p=Find(i);
                if(Find(i)!=p)
                {
                ans1=-1;
                break;
                }
            }
            if(du[i]==-1)
                ans1++;
            if(du[i]==1)
                ans2++;
            if(du[i]<=-2||du[i]>=2)
            {
                ans1=-1;
                break;
            }
        }
        if((ans1==0&&ans2==0)||(ans1==1&&ans2==1))
            printf("Ordering is possible.\n");
        else
            printf("The door cannot be opened.\n");
    }
    return 0;
}