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.
'''
# Read input from stdin and provide input before running code

name = raw_input('What is your name?\n')
print 'Hi, %s.' % name
'''
def binarysearch(arr,target):
    if target<=arr[0]:
        return 0
    if target>=arr[-1]:
        return len(arr)-1

    low=0
    high=len(arr)-1
    while low<=high:
       mid=(low+high)/2
       if arr[mid]==target:
           return mid
       elif arr[mid]<target:
           low=mid+1
       else:
           high=mid-1
    return low

if False:
    a=input()
    target=input()
    print "inputs",a,target
    print binarysearch(a,target)

def NonDecreaseMin(arr,length):
    n=len(arr)
    stack=[arr[0]]
    for a in arr[1:]:
        if a>=stack[-1]:
            stack.append(a)
        else:
            relocation=binarysearch(stack,a)
            stack[relocation]=a
    if len(stack)<length:
        return -1
    else:
        return stack[length-1]

T=int(raw_input())
for i in range(T):
	raw_input()
	arr=map(int,raw_input().split())
	length=int(raw_input())
	print NonDecreaseMin(arr,length)