# import sys
# input = sys.stdin.readline
def mp():return map(int,input().split())
def lmp():return list(map(int,input().split()))
import math
import bisect
from copy import deepcopy as dc
from itertools import accumulate
from collections import Counter, defaultdict, deque
def ceil(U,V):return (U+V-1)//V
def modf1(N,MOD):return (N-1)%MOD+1
inf = int(1e10)
mod = int(1e9+7)

n,k = mp()
a = lmp()
c = 0
for i in a:c^=i
a.append(c)
n += 1
u = modf1(k,n)
print(a[u-1])