#include<cstdio>

#include<cstring>

#include<vector>

using namespace std;

int a[],f[],b[];

bool vis[];

int find(int x)

{

    return f[x]==-?x:f[x]=find(f[x]);

}

void combine(int x,int y)

{

    int n=find(x);

    int m=find(y);

    if(n!=m) f[n]=m;

}

bool oula()

{

    int st=-;

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

    {

        if(a[i]||b[i])

            if(st==-)st=find(i);

            else if(st!=find(i)) return false;

    }

    vector<int>v;

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

        if(a[i]!=b[i])

            v.push_back(a[i]-b[i]);

    return v.size()==||v.size()==&&v[]*v[]==-;

}

int main()

{

    int t,n;

    char s[];

    scanf("%d",&t);

    while(t--)

    {

        memset(a,,sizeof a);

        memset(f,-,sizeof f);

        memset(b,,sizeof b);

        int ans=,cnt=;

        bool flag=;

        scanf("%d",&n);

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

        {

            scanf("%s",&s);

            int l=strlen(s);

            int x=s[]-'a',y=s[l-]-'a';

            a[x]++,b[y]++;

            combine(x,y);

        }

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

        else puts("The door cannot be opened.");

    }

    return ;

}