Shinchan and Kazama both are playing with numbers. Shinchan gives Kazama an array of numbers and asks him to tell the minimum possible last number of a non decreasing sequence of length L.
Note- Check the sample I/O for more clarity.

INPUT-
Input consists of number of test cases T. Each test case contains size of array i.e N.
Next line contains N space separated elements of array.
Next line contains length of the non decreasing sequence i.e. L.

OUTPUT-
You have to print the minimum possible last number of a sequence and if their is no non-decreasing sequence of length L, then print "-1" without the quotes.

CONSTRAINTS-
1 ≤ T ≤ 100
1 ≤ N ≤ 10^6
1 ≤ a[i] ≤ 10^6
1 ≤ L ≤ N

SAMPLE INPUT
1
7
9 7 2 5 4 11 12
3

SAMPLE OUTPUT
11

Explanation

In sample input, possible non-decreasing sequences of length L=3 are
(9,11,12) , (7,11,12) , (2,5,11) , (2,4,11) , (2,5,12) , (2,4,12) , (2,11,12) , (5,11,12) , (4,11,12)
and the minimum last number is 11 for the sequences (2,5,11) and (2,4,11). Hence, the answer is 11.

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