def main0(n,s,e,a):
  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:
    return -1
  else:
    return seen[n+1]-1
def main1(n,s,e,a):
  # a[i]<=10^9~2^30
  # 各iについてハミルトン距離が1のものを列挙→連想配列{数字:idx}の中から当てはまるものを探す
  a.append(s)
  a.append(e)
  g=[set() for _ in range(n+2)]
  d={}
  for i,x in enumerate(a):
    if x in d:
      d[x].append(i)
    else:
      d[x]=[i]
  for i,x in enumerate(a):
    for j in range(30):
      if x^(1<<j) in d:
        for k in d[x^(1<<j)]:
          g[i].add(k)
          g[k].add(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:
    return -1
  else:
    return seen[n+1]-1

if __name__=='__main__':
  n=int(input())
  s,e=map(int,input().split())
  a=list(map(int,input().split()))
  #ret0=main0(n,s,e,a[:])
  ret1=main1(n,s,e,a[:])
  #print(ret0)
  print(ret1)