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Note：
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#include <queue>
#include <math.h>
#include <stack>
#include <stdio.h>
#include <iostream>
#include <vector>
#include <iomanip>
#include <string.h>
#include <algorithm>
using namespace std;
#define LL long long
const int N = 1e6 + 10;
const int INF = 0x3f3f3f3f;
int tr[N*2][2] , a[N] , idx;
void add(int x)
{
	int len = 0;
	for(int i = 30 ; ~i ; i-- )
	{
		int k = (x & (1 << i)) ? 1 : 0;
		if(!tr[len][k])
			tr[len][k] = ++idx;
		len = tr[len][k];
	}
}
int find(int x)
{
	int len = 0 , ans = 0;
	for(int i = 30 ; ~i ; i-- )
	{
		int k = (x & (1 << i)) ? 0 : 1;
		if(tr[len][k])
		{
			ans += (1 << i);
			len = tr[len][k];
		}
		else 
			len = tr[len][k^1];
	}
	return ans;
}
int main()
{
	int n;
	cin >> n;
	for(int i = 1 ; i <= n ;i ++)
	{
		cin >> a[i];
		add(a[i]);
	}
	int maxx = 0;
	for(int i = 1 ; i <= n ; i++)
		maxx = max(maxx , find(a[i]) );
	cout << maxx << endl;
	return 0;
}