#include <iostream>

 #include <cstdio>

 #include <cstring>

 #include <cmath>

 #include <algorithm>

 #include <string>

 #include <vector>

 #include <set>

 #include <map>

 #include <stack>

 #include <queue>

 #include <sstream>

 #include <iomanip>

 using namespace std;

 typedef long long LL;

 const int INF=0x4fffffff;

 const int EXP=1e-;

 const int MS=;

 const int SIZE=;

 int n;

 char word[MS];

 int od[SIZE],id[SIZE];

 int appear[SIZE];

 int fa[SIZE];

 struct edge

 {

       int u,v;

 }edges[MS];

 void fa_init()

 {

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

             fa[i]=-;

 }

 int find(int x)

 {

       int s;

       for(s=x;fa[s]>=;s=fa[s]);

       while(s!=x)

       {

             int tmp=fa[x];

             fa[x]=s;

             x=tmp;

       }

       return s;

 }

 void merge(int x,int y)

 {

       int f1=find(x);

       int f2=find(y);

       int tmp=fa[f1]+fa[f2];

       if(fa[f1]>fa[f2])

       {

             fa[f1]=f2;

             fa[f2]=tmp;

       }

       else

       {

             fa[f2]=f1;

             fa[f1]=tmp;

       }

 }

 bool connect()

 {

       int u,v,i;

       fa_init();

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

       {

             u=edges[i].u;

             v=edges[i].v;

             if(u!=v&&find(u)!=find(v))

                   merge(u,v);

       }

       int first=-;

       for( i=;i<SIZE;i++)

       {

             if(appear[i]==)

                   continue;

             if(first==-)

                   first=i;

             else if(find(i)!=find(first))

                   break;

       }

       if(i<SIZE)

             return false;

       return true;

 }

 int main()

 {

       int u,v;

       int i,j;

       int T;

       scanf("%d",&T);

       while(T--)

       {

             memset(od,,sizeof(od));

             memset(id,,sizeof(id));

             memset(appear,,sizeof(appear));

             scanf("%d",&n);

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

             {

                   scanf("%s",word);

                   u=word[]-'a';

                   v=word[strlen(word)-]-'a';

                   od[u]++;

                   id[v]++;

                   appear[u]=appear[v]=;

                   edges[i].u=u;

                   edges[i].v=v;

             }

             bool Euler=true;

             int one=,none=;

             for(i=;i<SIZE;i++)

             {

                   if(appear[i]==)

                         continue;

                   if(od[i]-id[i]>=||id[i]-od[i]>=)

                   {

                         Euler=false;

                         break;

                   }

                   if(od[i]-id[i]==)

                   {

                         one++;

                         if(one>)

                         {

                               Euler=false;

                               break;

                         }

                   }

                   if(id[i]-od[i]==)

                   {

                         none++;

                         if(none>)

                         {

                               Euler=false;

                               break;

                         }

                   }

             }

             if(one!=none)

                   Euler=false;

             if(connect()==false)

                   Euler=false;

             if(Euler)

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

             else

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

       }

       return ;

 }