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import java.io.*;
import java.lang.Integer;
class Main {
    static int N = 3000010; // ??N???1000000
    static int[][] t = new int[N][2];
    static int idx = 0;
    static void insert(int num) {
        int p = 0;
        for (int x = 30; x >= 0; --x) {
            int c = (num >> x) & 1;
            if (t[p][c] == 0) {
                t[p][c] = ++idx;
            }
            p = t[p][c];
        }
    }
    static int compare(int num) {
        int p = 0;
        int max = 0;
        for (int x = 30; x >= 0; --x) {
            int c = (num >> x) & 1;
            if (t[p][1 - c] == 0) {
                max = (max << 1) | 1;
                p = t[p][c];
            } else {
                max = (max << 1) | 0;
                p = t[p][c];
            }
        }
        return max;
    }
    public static void main(String[] args) throws Exception {
        BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter buw = new BufferedWriter(new OutputStreamWriter(System.out));
        int n = Integer.valueOf(buf.readLine());
        String[] params = buf.readLine().split(" ");
        for (int i = 0; i < n; ++i) {
            int num = Integer.valueOf(params[i]);
            insert(num);
        }
        int max = 0;
        for (int i = 0; i < n; ++i) {
            int num = Integer.valueOf(params[i]);
            int m = compare(num);
            if (m > max) {
                max = m;
            }
        }
        buw.write(max + "");
        buw.flush();
        buf.close();
        buw.close();
    }
}

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