#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
struct Node {
	int s[2];
} tr[maxn * 31];
int n, a, idx, ans;
void ins(int a) {
	for (int u = 0, d = 30; d >= 0; d--) {
		int x = (a >> d) & 1;
		int &s = tr[u].s[x];
		if (!s) s = ++idx;
		u = s;
	}
}
int cal(int a) {
	int res = 0;
	for (int u = 0, d = 30; d >= 0; d--) {
		int x = (a >> d) & 1;
		int s = tr[u].s[x], s2 = tr[u].s[x^1];
		if (s2)
			res += (1<<d), u = s2;
		else
			u = s;
	}
	return res;
}
int main() {
	scanf("%d", &n);
	for (int i = 0; i < n; i++) {
		scanf("%d", &a);
		if (i) ans = max(ans, cal(a));
		ins(a);
	}
	printf("%d\n", ans);
	return 0;
}