#include<iostream>

#include<cstring>

#include<algorithm>

using namespace std;

typedef struct char_c

{

    char ch[6];

}char_c;

int fun(char_c a,char_c b)

{

    int i;

    for(i=0;i<5;i++)

    {

      if(a.ch[i]>b.ch[i]){return 1;break;}

      if(a.ch[i]<b.ch[i]) {return 0;break;}

    }

}

int main()

{

    int n;

    const int N=1001;

    char_c ch1[N];

    cin>>n;

    while(n--)

      {

          int m;

          cin>>m;

          int i;

          for( i = 0; i < m; i++ )

             cin>>ch1[i].ch;

         sort(ch1,ch1+m,fun);

         // for( i = 0; i < m; i++ )

            cout<<ch1[m-1].ch<<endl;

        }

  return 0;

}