#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 100005

int n;
ll a[MAX_N];
int f[MAX_N][50];
const ll INF = 1234567812345;
ll two[50];

ll dfs(int l, int r, int d, ll res){
    if(l == r)return INF;

    int m = -1;
    srep(i,l,r){
        if(f[i][d] == 1 && m == -1){
            m = i;
        }
    }
    if(m == -1) m = r;

    if(d == 0){
        if(m == l || m == r){
            return res;
        }else{
            return res + 1;
        }
    }

    if(m == l){
        return dfs(l,r,d-1,res);
    }else if(m == r){
        return dfs(l,r,d-1,res);
    }else{
        res += two[d];
        return min(dfs(l,m,d-1,res), dfs(m,r,d-1,res));
    }

}

int main() {
    cin >> n;
    rep(i,n)cin >> a[i];
    sort(a,a+n);
    rep(i,n){
        ll a_ = a[i];
        rep(j,50){
            f[i][j] = a_ % 2;
            a_ /= 2;
        }
    }
    two[0] = 1;
    srep(i,1,50)two[i] = two[i-1] * 2;

    ll ans = dfs(0, n, 40, 0);

    cout << ans << endl;
    return 0;
}