n, k = map(int, input().split())
a = list(map(int, input().split()))
for i in range(1000000):
    x = 0
    for j in range(1, n + 1):
        x ^= a[-j]
    a.append(x)
    l = len(a)
    if l % 2 == 0 and a[-(l // 2):] == a[:(l // 2)]:
        break
shuki = l // 2
print(a[(k - 1) % shuki])