1 #pragma comment(linker, "/STACK:1024000000,1024000000")
  2 #include<iostream>
  3 #include<cstdio>
  4 #include<cstring>
  5 #include<cmath>
  6 #include<math.h>
  7 #include<algorithm>
  8 #include<queue>
  9 #include<set>
 10 #include<bitset>
 11 #include<map>
 12 #include<vector>
 13 #include<stdlib.h>
 14 #include <stack>
 15 using namespace std;
 16 int dirx[]={0,0,-1,1};
 17 int diry[]={-1,1,0,0};
 18 #define PI acos(-1.0)
 19 #define max(a,b) (a) > (b) ? (a) : (b)
 20 #define min(a,b) (a) < (b) ? (a) : (b)
 21 #define ll long long
 22 #define eps 1e-10
 23 #define MOD 1000000007
 24 #define N 100006
 25 #define inf 1e12
 26 int n;
 27 int u[N],v[N];
 28 int in[N],out[N];
 29 int vis[N];
 30 int fa[N];
 31 int num;
 32 void init(){
 33    memset(in,0,sizeof(in));
 34    memset(out,0,sizeof(out));
 35    memset(vis,0,sizeof(vis));
 36    for(int i=0;i<N;i++){
 37        fa[i]=i;
 38    }
 39    num=0;
 40 }
 41 /
 42 int find(int x){
 43    return fa[x]==x?x:fa[x]=find(fa[x]);
 44 }
 45 void merge(int x,int y){
 46    int root1=find(x);
 47    int root2=find(y);
 48    if(root1==root2) return;
 49    fa[root1]=root2;
 50 }
 51 //
 52 void solve(){
 53
 54     for(int i=0;i<n;i++){
 55         merge(u[i],v[i]);
 56     }
 57     int i=0;
 58     for(i;!vis[i];i++);
 59
 60     int x=find(i);//判断能否连通
 61     for(int j=i+1;j<26;j++){
 62         if(vis[j]){
 63            int y=find(j);
 64            if(x!=y){
 65                printf("The door cannot be opened.\n");
 66                return;
 67            }
 68         }
 69     }
 70
 71     int flag=1;
 72     int cnt=0;
 73     for(int i=0;i<26;i++){
 74         if(vis[i]){
 75            if(in[i]!=out[i]){
 76               if(in[i]==out[i]-1) cnt++;
 77               else if(in[i]==out[i]+1) cnt++;
 78               else{
 79                   flag=0;
 80                   break;
 81               }
 82            }
 83            if(cnt>2){
 84                flag=0;
 85                break;
 86            }
 87         }
 88     }
 89     if(flag){
 90         printf("Ordering is possible.\n");
 91     }
 92     else{
 93         printf("The door cannot be opened.\n");
 94     }
 95
 96 }
 97 int main()
 98 {
 99    int t;
100    scanf("%d",&t);
101    while(t--){
102
103          init();
104
105          char s[1006];
106          scanf("%d",&n);
107          for(int i=0;i<n;i++){
108              scanf("%s",s);
109              int len=strlen(s);
110              int a=s[0]-'a';
111              int b=s[len-1]-'a';
112              u[i]=a,v[i]=b;
113              in[a]++,out[b]++;
114              vis[a]=1;
115              vis[b]=1;
116          }
117          solve();
118    }
119     return 0;
120 }