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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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