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.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        PrintWriter printWriter = new PrintWriter(System.out);
        int n = scanner.nextInt();
        int k = scanner.nextInt();
        Integer arr[] = new Integer[n];
        for (int i = 0; i < arr.length; i++) {
            arr[i] = scanner.nextInt();
        }

        Arrays.sort(arr);

        boolean check = true;
        int count = 0;
        int result = arr[0]-1;
        if (k == 0) {
            if (arr[0] <= 1) {
                check = false;
            }

        } else {

            for (int i = 0;i<n&& arr[i] <= arr[k - 1]; i++) {
                count++;
                //System.out.println("a");
            }
            //System.out.println(count);
            result = arr[k-1];
        }
        if (count != k) check = false;

        if (check)
            printWriter.println(result);
        else printWriter.println(-1);

        printWriter.flush();
        printWriter.close();
    }
}