1 #include <bits/stdc++.h>

 2 //#define loveGsy

 3 using namespace std;

 4 const int N = 1e5 + 10;

 5 int trie[N * 31][2]; //每个数用31位二进制构造Trie树,每个节点为0或1

 6 int a[N], n, ans, tot = 1;

 7

 8 void insert(int x) {//构建trie树

 9     int p = 0;

10     for (int k = 30; k >= 0; k--) {//高位向低位枚举

11         int t = x >> k & 1;//计算x的第k位是1还是0    0~30

12         if (!trie[p][t]) trie[p][t] = ++tot;

13         p = trie[p][t];

14     }

15 }

16

17 int search(int x) {

18     int p = 0, tmp = 0;

19     for (int k = 30; k >= 0; k--) {

20         int t = x >> k & 1;//取出x第k位

21         if (trie[p][t ^ 1]) {

22             p = trie[p][t ^ 1];//贪心思想，走相反位

23             tmp = tmp + (1 << k);

24         }

25         else p = trie[p][t];

26     }

27     return tmp;

28 }

29

30 int main() {

31 #ifdef loveGsy

32     freopen("xor.in", "r", stdin);

33     freopen("xor.out", "w", stdout);

34 #endif

35     cin >> n;

36     for (int i = 1; i <= n; i++) {

37         scanf("%d", &a[i]);

38         insert(a[i]);

39         ans = max(ans, search(a[i]));

40     }

41     cout << ans << endl;

42     return 0;

43 }