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.
for _ in range(input()):
    n = input()
    arr= map(int, raw_input().split())
    klen= input()
    minArr = [0] * n
    currLen = 1
    minArr[0] = arr[0]
    for i in range(1, n):
        if arr[i] < minArr[0]:
            minArr[0] = arr[i]
        elif arr[i] > minArr[currLen-1]:
            if currLen < klen:
                minArr[currLen] = arr[i]
                currLen += 1
        else:
            low = -1
            high= currLen - 1
            while low < high:
                mid = low + (high - low) / 2
                if minArr[mid] < arr[i]:
                    low = mid + 1
                else:
                    high = mid
            minArr[high] = arr[i]
    if currLen < klen:
        print "-1"
    else:
        print minArr[klen - 1]