#define _USE_MATH_DEFINES
#include<iostream>
#include<vector>
#include<algorithm>
#include<cmath>
#include<string>
#include<iomanip>
#include<numeric>
#include<queue>
#include<deque>
#include<stack>
#include<set>
#include<map>
#include<random>
#include<bitset>
#include<cassert>
#include<complex>
#include<fstream>
#include<cstdlib>
#include<functional>
#include<array>
using namespace std;
typedef long long ll;
const int mod=998244353;
const int dx[]={1,0,0,-1},dy[]={0,1,-1,0};
vector<int>G[1002];
int dist[1002];
int main(){
	int n,s[1002];
	cin>>n;
	for(int i=0;i<n+2;i++)
		cin>>s[i];
	for(int i=0;i<n+2;i++)
		for(int j=0;j<n+2;j++)
			if(__builtin_popcount(s[i]^s[j])<=1)
				G[i].push_back(j);
	fill(dist+1,dist+n+2,-1);
	queue<int>que;
	que.push(0);
	while(que.size()){
		int v=que.front();
		que.pop();
		for(auto x:G[v]){
			if(dist[x]==-1){
				dist[x]=dist[v]+1;
				que.push(x);
			}
		}
	}
	cout<<(dist[1]==-1?-1:dist[1]-1)<<endl;
}