#include<iostream>

#include<cstring>

using namespace std;

const int M = ;

int f[M];

int in[M],out[M];

int fd(int x) {return f[x]==x? x:f[x]=fd(f[x]);}

void mix(int a,int b) {a=fd(a);b=fd(b);if(a!=b) f[a]=b;}

void init(){

    for(int i = ;i <= M;i ++){

        f[i] = i;

    }

    memset(in,,sizeof(in));

    memset(out,,sizeof(out));

}

int main()

{

    string s;

    int t,n;

    cin>>t;

    while(t--){

        init();

        cin>>n;

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

            cin>>s;

            int len = s.size();

            int x = s[] - 'a';

            int y = s[len-] - 'a';

            in[x]++; out[y]++;

            //cout<<x<<" "<<y<<endl;

            mix(x,y);

        }

        int ans = ;

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

            if(i==f[i]&&(in[i]||out[i])){

                ans++;

            }

        }

        //cout<<ans<<endl;

        bool flag = true;

        int num1 = ,num2 = ;

        if(ans == ){

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

            if(in[i]!=out[i]){

                if(in[i]+==out[i]) num1++;

                else if(in[i]==out[i]+) num2++;

                else{

                    flag = false;break;

                }

            }

            }

            if(num1&&num2&&num1+num2>) flag = false;

        }

        else flag = false;

        if(flag) cout<<"Ordering is possible."<<endl;

        else cout<<"The door cannot be opened."<<endl;

    }

    return ;

}