# Sagar's Gift

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#
#   Today is Sagar's birthday. He got array of numbers as a gift by his father. His father told him that he has
#   another gift if Sagar is able make largest number by concatenating the numbers and swapping the digits of numbers.
#   Help Sagar to make largest number from the given numbers.
#
#   Input:
#   First line contains number of testcases T Next line contain value of number of values in array N Followed
#   by N space separated number
#
#   Output:
#   Output the answer.
#
#   Constraint :
#   1 <= T <= 10
#   1 <= N <= 100
#   1 <= a[i] <= 10000
#
#   SAMPLE INPUT
#   2
#   5
#   1 2 20 31 5
#   4
#   9 1 5 10
#
#   SAMPLE OUTPUT
#   5322110
#   95110
#
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