#include<bits/stdc++.h>
#define pii array<int,2>
using namespace std;
int T,n,r[30],c[30],f[30],st,ed,lc;
char ch[1005];
vector<int>v[30];
stack<int>ans;
int fd(int x){
    if(x==f[x])return x;
    return f[x]=fd(f[x]);
}
bool solve(){
    for(int i=1;i<=26;i++){
        if(c[i]>r[i]+1||r[i]>c[i]+1)return 0;
        if(c[i]==r[i]+1){
            if(st)return 0;
            st=i;
        }
        if(r[i]==c[i]+1){
            if(ed)return 0;
            ed=i;
        }
        if(c[i]+r[i]){
            if(!lc)lc=fd(i);
            if(lc!=fd(i))return 0;
        }
    }

    return 1;
}
int main(){
    scanf("%d",&T);
    while(T--){
        scanf("%d",&n);
        for(int i=1;i<=26;i++)v[i].clear(),f[i]=i;
        memset(r,0,sizeof r);
        memset(c,0,sizeof c);
        st=ed=lc=0;
        for(int i=1;i<=n;i++){
            scanf("%s",ch+1);
            int len=strlen(ch+1),x=ch[1]-'a'+1,y=ch[len]-'a'+1;
            v[x].push_back(y);
            c[x]++;r[y]++;
            int fx=fd(x),fy=fd(y);
            if(fx!=fy)f[fx]=fy;
        }
        printf(solve()?"Ordering is possible.\n":"The door cannot be opened.\n");
    }
    return 0;
}