import sys
readline = sys.stdin.readline

N = int(readline())
s,g = map(int,readline().split())

A = [s] + list(map(int,readline().split())) + [g]
N += 2

def can_connect(X, Y):
  diff = 0
  while X or Y:
    if (X & 1) ^ (Y & 1):
      diff += 1
      if diff == 2:
        return False
    X >>= 1
    Y >>= 1
  return True
  
G = [[] for i in range(N)]
for i in range(N - 1):
  for j in range(i + 1, N):
    if can_connect(A[i], A[j]):
      G[i].append(j)
      G[j].append(i)

visited = [False] * N
from collections import deque
q = deque([])
q.append([0, 0])
while q:
  v, cost = q.popleft()
  if visited[v]:
    continue
  visited[v] = True
  if v == N - 1:
    print(cost - 1)
    break
  for child in G[v]:
    if visited[child]:
      continue
    q.append([child, cost + 1])
else:
  print(-1)