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.
# TAIWAN NUMBER ONE!!!!!!!!!!!!!!!!!!!
# TAIWAN NUMBER ONE!!!!!!!!!!!!!!!!!!!
# TAIWAN NUMBER ONE!!!!!!!!!!!!!!!!!!!
from sys import stdin, stdout
import math

#T = int(input())
#N = int(input())
#s = input()
N,K = [int(x) for x in stdin.readline().split()]
arr = [int(x) for x in stdin.readline().split()]

arr.sort()
count = 0

c = {}
num = []

for i in range(N):
    if arr[i] not in c:
        count = 1
        num.append(arr[i])
    else:
        count += 1
        
    c[arr[i]] = count

s = 0
if K==0 and num[0]==1:
    print(-1)
    quit()
elif K==0 and num[0]>1:
    print(1)
    quit()
    
for key in num:
    s += c[key]
    if s==K:
        print(key)
        quit()
        
print(-1)
  