#include <stdio.h>
#include <iostream>
#include <string.h>
#include <algorithm>
#include <math.h>
using namespace std;
const int N = 30;
bool vis[N]; ///判断当前字母是否出现过
int father[N];
int indegree[N],outdegree[N]; ///入度和出度
int _find(int x){
    if(x==father[x]) return x;
    return _find(father[x]);
}
int Union(int a,int b){
    int x = _find(a);
    int y = _find(b);
    if(x==y) return 0;
    father[x] = y;
    return 1;
}
void init(){
    memset(vis,false,sizeof(vis));
    memset(indegree,0,sizeof(indegree));
    memset(outdegree,0,sizeof(outdegree));
    for(int i=0;i<N;i++) father[i]=i;
}
int main()
{
    int tcase;
    scanf("%d",&tcase);
    while(tcase--){
        int n;
        char str[1005];
        scanf("%d",&n);
        init();
        while(n--){
            scanf("%s",str);
            int len = strlen(str);
            int s = str[0]-‘a‘;
            int e = str[len-1]-‘a‘;
            Union(s,e);
            vis[s] = vis[e] = true;
            indegree[e]++;
            outdegree[s]++;
        }
        int ans = 0;
        bool flag=false,flag1=false;
        int in=0,out=0;
        for(int i=0;i<N;i++){
            if(vis[i]){
                if(father[i]==i) ans++;
                if(indegree[i]!=outdegree[i]){
                    if(indegree[i]-outdegree[i]==1) in++;
                    else if(outdegree[i]-indegree[i]==1) out++;
                    else flag1 = true;
                }
            }
            if(ans>1){
                flag = true;
            }
        }
        if(!flag&&!flag1&&in==0&&out==0) printf("Ordering is possible.\n");
        else if(!flag&&!flag1&&in==1&&out==1) printf("Ordering is possible.\n");
        else printf("The door cannot be opened.\n");
    }
}