#include <iostream>
#include <tuple>
#include <cmath>
#include <string>
#include <cstring>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <algorithm>
#include <vector>
#include <fstream>
#include <iomanip>
#include <ctime>
#include <cctype>
#include <climits>
#include <chrono>
#include <array>
 
using namespace std;
 
typedef long long ll;
typedef vector<int> vi;
typedef vector< vector <int> > vvi;
typedef pair<int, int> pii;
typedef pair < pair < int, int >, int > piii;
typedef pair < pair <int, int > , pair <int, int> > piiii;
typedef pair<ll, ll> pll;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
 
#define FOR(i,a,b) for(int i = a; i < b; i ++)
#define RFOR(i,a,b) for(int i = a-1; i >= b; i --)
#define all(a) a.begin(), a.end()
#define endl '\n';
#define sz(x) (int)(x).size()
 
#define mp make_pair
#define pb push_back
#define ff first
#define ss second
 
template <typename T>
void pr(vector<T> &v) {
    FOR(i, 0, sz(v)) cout << v[i] << " ";
    cout << endl;
}
template <typename T>
void pr(vector<vector<T> > &v) {
    FOR(i, 0, sz(v)) { pr(v[i]); }
}
template <typename T>
void re(T &x) {
    cin >> x;
}
template <typename T>
void re(vector<T> &a) {
    FOR(i, 0, sz(a)) re(a[i]);
}
template <class Arg, class... Args>
void re(Arg &first, Args &... rest) {
    re(first);
    re(rest...);
}
template <typename T>
void pr(T x) {
    cout << x << endl;
}
template <class Arg, class... Args>
void pr(const Arg &first, const Args &... rest) {
    cout << first << " ";
    pr(rest...);
    cout << endl;
}
void ps() { cout << endl; }
template<class T, class... Ts>
void ps(const T& t, const Ts&... ts) {
    cout << t; if (sizeof...(ts)) cout << " "; ps(ts...);
}
 
const ll MOD  = 998244353;
#define inf 1e18;
#define INF INT_MAX
 
long double PI = 4*atan(1);
long double eps = 1e-12;

int n;
vi a;
vector<int> trips;
bool good[1 << 25] = {};

int dp[1 << 25] = {};

int recurse(int bm) {
    if(dp[bm] != -1) return dp[bm];


    int ans = 1e9;
    for(int i = 0; i < n; i++) {
        if(bm & (1 << i) && good[bm ^ (1 << i)]) {
            ans = min(ans, 1 + recurse(bm ^ (1 << i)));
        }
    }

    if(ans == 1e9) ans = 0;

    dp[bm] = ans;
    return ans;
}

int main() {
    //auto start = chrono::high_resolution_clock::now();
    ios_base::sync_with_stdio(0);cin.tie(0);
    //ofstream cout("output.txt");
    //ifstream cin("input.txt");
    #ifdef DEBUG
      freopen("input.txt", "r", stdin);
      freopen("output.txt", "w", stdout);
    #endif
    
    cin >> n;
    a.resize(n); re(a);

    

    FOR(i,0,n) FOR(j,i+1,n) FOR(k,j+1,n) if((a[i] ^ a[j] ^ a[k]) == 0) {trips.pb((1<<i) + (1<<j) + (1<<k)); }


    for(int x : trips) {
    //    cout << x << endl;
        good[x] = true;
    }




    for(int i = 0; i < (1 << n); i++) {
        for(int j = 0; j < n; j++) {
            if((i & (1 << j)) && good[i ^ (1 << j)]) {
                good[i] = true;
                break;
            }
        }
    }
    int ans = 100;
    for(int i = 0; i < (1 << n); i++) {
        if(!good[i]) {
            int cnt = 0;
            for(int j = 0; j < n; j++) {
                if(i & (1 << j)) cnt++;
            }
            ans = min(ans, n - cnt);
        }
    }

    // for(int i = 0; i < (1 << n); i++) {
    //     for(int j = 0; j < n; j++) {
    //         if(i & (1 << j)) {
    //             if(good[i ^ (1 << j)]) {
    //                 dp[i] = min(dp[i], dp[i ^ (1 << j)] + 1);
    //             } else {
    //                 dp[i] = 1;
    //                 break;
    //             }
    //         }
    //     }
    //     if(dp[i] == 100) dp[i] = 1;
    // }



    cout << ans << endl;
    
    
    //auto stop = chrono::high_resolution_clock::now();
    //auto duration = chrono::duration_cast<chrono::microseconds>(stop - start);
    //cout << duration.count() << endl;
    //cin.close();
    //cout.close();
}