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 java.util.Scanner;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Problem2 {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int k = scan.nextInt();
		
		List array = new ArrayList();
		
		for (int i = 0; i < n; i++) {
			array.add(scan.nextInt());
		}
		Collections.sort(array);
		
		System.out.println(Less(array, n, k));
	}
	
	public static int Less(List array, int n, int k) {
		
		int count = 0;
		int x = 0;
		
		if (k == n) {
			return (int) array.get(n-1);
		}
		
		for (int i = 0; i < n; i++) {
			if (k == 0) {
				if ((int) array.get(0) == 1) {
					return -1;
				}
				else {
					return 1;
				}
			}
			x = (int) array.get(i);
			count++;
			if (count == k) {
				if (n == 1) {
					return x;
				}
				else if ( (int)array.get(i+1)  == x) {
					return -1;
				}
				else
					return x;
			}
		}
		return -1;
	}
}