#include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;
const int N=30;
int n;
int din[N],dout[N],p[N];
bool st[N];

int find(int x)
{
    if(p[x]!=x)p[x]=find(p[x]);
    return p[x];
}

int main()
{
    int T;
    cin>>T;
    char str[1010];
    while(T--){
        scanf("%d",&n);
        memset(din,0,sizeof din);
        memset(dout,0,sizeof dout);
        memset(st,0,sizeof st);
        for(int i=0;i<26;i++)p[i]=i;

        for(int i=0;i<n;i++){
            scanf("%s",str);
            int len=strlen(str);
            int a=str[0]-'a',b=str[len-1]-'a';
            st[a]=st[b]=true;
            dout[a]++,din[b]++;
            p[find(a)]=find(b);
        }

        int start=0,end=0;
        bool success=true;
        for(int i=0;i<26;i++){
            if(din[i]!=dout[i]){
                if(din[i]==dout[i]+1)end++;
                else if(din[i]+1==dout[i])start++;
                else {
                    success=false;
                    break;
                }
            }
        }
        if(success && !(!start && !end || start==1 &&end==1))success=false;

        int rep=-1;
        for(int i=0;i<26;i++){
            if(st[i]){
                if(rep==-1)rep=find(i);
                else if(rep!=find(i)){
                    success=false;
                    break;
                }
            }
        }
        if(success)puts("Ordering is possible.");
        else puts("The door cannot be opened.");
    }
    return 0;
}