// Problem A. Eleven Divisible
// By Anant Choksuriwong, Dept. of Computer Engineering, PSU Hatyai 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int isElevenDiv(char x[1000])
{
    int i,digit,total=0;
    
    for (i=0; i < strlen(x); i++)
    {
      digit = x[i]-'0';
      if (i%2==0)
         total += digit;
      else
         total -= digit;
    }
    
    if ((total==0) || (total%11==0))
       return 1;
    else
       return 0;
}
// return 1 if int value of l > int value of r
int cmp(char l[1000],char r[1000])
{ 
    int i,dl,dr;
    
    if (strlen(l) > strlen(r))
       return 1;
    else if (strlen(l) < strlen(r))
       return -1;
    else
        for (i=0; i < strlen(l); i++)
        {
            dl = l[i] - '0';
            dr = r[i] - '0';
            if ( dl > dr)
              return 1;
            else if ( dl < dr)
              return -1;
        }
    return 0;
}

int main()
{
  int i,j;
  int g,n;
  char nb[1000][1000],max[1000];
  
  scanf("%d",&g);
  for (i=0; i < g; i++)
  {
     strcpy(max,"0");
     scanf("%d",&n);
     for (j=0; j< n; j++)
     {
       scanf("%s",nb[j]);
       if (isElevenDiv(nb[j]))
       {
          //printf("%s ",nb[j]);
          if (cmp(nb[j],max) == 1)
             strcpy(max,nb[j]);
       }       
     }
     printf("%s\n",max);
  }
  
  return 0;    
}