Never solve able

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;109]
(i.e. 1≤x≤109
) 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⋅105
, 0≤k≤n
). The second line of the input contains n
integer numbers a1,a2,…,an
(1≤ai≤109
) — the sequence itself.

Output
Print any integer number x
from range [1;109]
such that exactly k
elements of given sequence is less or equal to x
.

If there is no such x
, print "-1" (without quotes).