#include <bits/stdc++.h>
using namespace std;
#define rep(i, x, limit) for (long long i = (long long)x; i < (long long)limit; i++)
#define REP(i, x, limit) for (long long i = (long long)x; i <= (long long)limit; i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define el '\n'
#define spa " "
#define Yes cout << "Yes" << el
#define No cout << "No" << el
#define YES cout << "YES" << el
#define NO cout << "NO" << el
#define inp(x) for(auto &i:x)cin>>i
#define eps (1e-10)
#define Equals(a,b) (fabs((a) - (b)) < eps )
#define debug(x) cerr << #x << " = " << x << el
using ll = long long;
using ull = unsigned long long;
using i128 = __int128_t;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vs = vector<string>;
using vb = vector<bool>;
const double pi = 3.141592653589793238;
const int inf = 1073741823;
const ll infl = 1LL << 60;
const string ABC = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const string abc = "abcdefghijklmnopqrstuvwxyz";
const ll MOD = 998244353;
#include<atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using vm = vector<mint>;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll n,st,go;cin>>n>>st>>go;
  vl S(n);inp(S);
  S.push_back(st);
  S.push_back(go);
  map<ll,vl> G;
  rep(i,0,n+2){
    ll b=S[i];
    rep(j,0,30){
      ll bb=b^(1<<j);
      rep(k,i+1,n+2){
        if(bb==S[k]){
          G[b].push_back(S[k]);
          G[S[k]].push_back(b);
          break;
        }
      }
    }
  }
  map<ll,ll> ans;
  queue<ll> que;
  ans[st]=0;
  que.push(st);
  while(!que.empty()){
    ll q=que.front();que.pop();
    for(auto to:G[q]){
      if(ans.count(to))continue;
      ans[to]=ans[q]+1;
      if(to==go){
        cout<<ans[go]-1<<el;
        return 0;
      }
      que.push(to);
    }
  }
  cout<<-1<<el;
}