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#include <bits/stdc++.h>
#define F first
#define S second
#define el cout << '\n'
#define maxn 100005
#define faster ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(0);
#define For(i,a,b) for ( int i = a;  i <= b; i++)

using namespace std;

int n, child[maxn][2], cnt = 0, a[maxn];
void ThemVaoTrie(int s)
{
    int u = 0;
    for(int i = 30; i >= 0; i--)
    {
        int c = (s >> i) & 1;
        if (child[u][c] == 0) {cnt++; child[u][c] = cnt; }
        u = child[u][c];
    }
}

int solve(int x)
{
    int u = 0; int res = 0;
    for(int i = 30; i >= 0; i--)
    {
        int c = (x >> i) & 1;
        if (child[u][c ^ 1] != -1)
        {
            res += (1LL << i);
            u = child[u][c ^ 1];
        }
        else u = child[u][c];
    }
    return res;
}

int main()
{
    faster
    cin >> n;
    memset(child, -1, sizeof child);
    int ans = -1;

    For(i,1,n)
    {
        cin >> a[i];
        ThemVaoTrie(a[i]);
    }

    For(i,1,n)
    {
        ans = max(ans, solve(a[i]));
    }
    cout << ans;
}