You are given a sequence of integers of length n and integer number k. You should print any integer number x in the range of [1; 10^9] (i.e. 1 ≤ x ≤ 10^9) such that exactly k elements of given sequence are less than or equal to x.

Note that the sequence can contain equal elements.

If there is no such x, print "-1" (without quotes).

Input

The first line of the input contains integer numbers n and k (1 ≤ n ≤ 2 ⋅ 10^5, 0 ≤ k ≤ n). The second line of the input contains n integer numbers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 10^9) — the sequence itself.

Output

Print any integer number x from range [1; 10^9] such that exactly k elements of given sequence is less or equal to x.

If there is no such x, print "-1" (without quotes).

Examples

Input

7 4
3 7 5 1 10 3 20


Output

6

Input

7 2
3 7 5 1 10 3 20


Output

-1

Note

In the first example 5 is also a valid answer because the elements with indices [1, 3, 4, 6] is less than or equal to 5 and obviously less than or equal to 6.

In the second example you cannot choose any number that only 2 elements of the given sequence will be less than or equal to this number because 3 elements of the given sequence will be also less than or equal to this number.
import sys

n,k = map(int,sys.stdin.readline().strip().split())

a = sys.stdin.readline()

def findX(n,k,a):
    a = a.strip().split()
    a_dict = {}
    for num in a:
        try:
            a_dict[int(num)] += 1
        except:
            a_dict[int(num)] = 1
    a.sort()
    numbers = list(a_dict)
    numbers.sort()
    if k < 1:
        if numbers[0]<2:
            return -1
        else:
            return 1
    moreThen = 0
    position = 0
    while moreThen<k and position<len(numbers):
        moreThen+=a_dict[numbers[position]]
        position+=1
    if position<len(numbers)+1:
        if moreThen==k:
            return numbers[position-1]
    return -1
    
def doTest():
    assert findX(7,4,'3 7 5 1 10 3 20')==5
    assert findX(7,2,'3 7 5 1 10 3 20')==-1
    assert findX(1,0,'1')==-1
    assert findX(1,0,'2')==1
    assert findX(1,0,'1')==-1
    
#doTest()
    
print(findX(n,k,a))