n=int(input())
s,e=map(int,input().split())
a=list(map(int,input().split()))
a.append(s)
a.append(e)
g=[[] for _ in range(n+2)]
for i in range(n+1):
  for j in range(i+1,n+2):
    x=a[i]^a[j]
    cnt=bin(x).count('1')
    if cnt<=1:
      g[i].append(j)
      g[j].append(i)
from collections import deque
todo=deque([n])
seen=[-1]*(n+2)
seen[n]=0
while todo:
  v=todo.popleft()
  for nv in g[v]:
    if seen[nv]==-1:
      seen[nv]=seen[v]+1
      todo.append(nv)
if seen[n+1]==-1:
  print(-1)
else:
  print(seen[n+1]-1)