func main()
	var n: int :: cui@inputInt()
	var k: int :: cui@inputInt() - 1
	var a: []bit64 :: #[n + 1]bit64
	for i(0, n - 1)
		do a[i] :: cui@inputInt() $ bit64
		do a[n] :: a[n].xor(a[i])
	end for
	
	var ans: bit64 :: a[k % (n + 1)]
	do cui@print("\{ans $ int}\n")
end func