from collections import defaultdict, deque

n = int(input())
s, e = map(int, input().split())
A = list(map(int, input().split()))
A = [s] + A + [e]
nei_dict = defaultdict(list)
for i in range(n + 1):
    for j in range(i + 1, n + 2):
        num = A[i] ^ A[j]
        cnt = 0
        while num != 0:
            if num % 2 == 1:
                cnt += 1
                if cnt == 2:
                    break
            num //= 2
        if cnt == 1:
            nei_dict[i].append(j)
            nei_dict[j].append(i)

seen = set([0])
dq = deque([(0, 1)])
while dq:
    curr, cnt = dq.popleft()
    if curr == n + 1:
        print(cnt - 2)
        exit()
    for np in nei_dict[curr]:
        if np in seen:
            continue
        seen.add(np)
        dq.append((np, cnt + 1))
print(-1)