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.Arrays;
import java.util.Scanner;


public class Main {
    
    public static void main(String[] args) {
        
		Scanner input = new Scanner(System.in);
              
                int n = input.nextInt();
                int k = input.nextInt();
				
		Integer [] array = new Integer[n];
                
		for(int i = 0 ; i < n; i++)
			array[i] = input.nextInt();
			
		Arrays.sort(array);
                
		if(k == 0){
			if(array [0] > 1){
				System.out.println("1");
				}
                        else{
				System.out.println("-1");
				}
                        
			}else if(n==k){
				System.out.println(array[n-1]);
			}
			else{
				
				if(array [k] > array[k-1]){
					System.out.println(array[k-1]);
				}else{
					System.out.println("-1");
				}
			}
		
	}
}
    

