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.
class Solution():

    def solve(self, n, k, seq):

        seq.sort()

        if k == 0:
            x = seq[0] - 1
        else:
            x = seq[k - 1]
       
        
        count = 0
        for i in range(0, n):
            if seq[i] <= x:
                count += 1

        if x < 1 or count != k:
            return -1

        return x

if __name__ == '__main__':

    sol = Solution()

    in1 = input().split()
    n = int(in1[0])
    k = int(in1[1])
    s = input().split()
    s = list(map(int, s))

    print(sol.solve(n, k, s)) 
            
