TAAND

#include <iostream>
#include <set>
#include <string.h>
#include <stdio.h>

using namespace std;

int main()
{
    long long int N;
    scanf("%lld", &N);

    unsigned long long int arr[32][2];

    long long int marked[32], maxn = -1;

    memset(arr, 0, sizeof(int)*32*2);
    fill_n(marked, 32, 0);

    for(long long int i = 0; i<N; i++){

        unsigned long long int t;
        scanf("%u", &t);

        int pow = 0;
        unsigned long long int num = 1<<pow;

        while(num <= t){
            if((num & t) > 0){
                marked[pow]++;
                if((marked[pow] > 1) && (maxn < pow))
                    maxn = pow;
                if(arr[pow][0] < t){
                    arr[pow][1] = arr[pow][0];
                    arr[pow][0] = t;
                } else if(arr[pow][1] < t)
                    arr[pow][1] = t;
            }
            pow++;
            num = 1<<pow;
        }
    }
    if(maxn == -1) printf("0\n");
    else
        printf("%u\n", (arr[maxn][0] & arr[maxn][1]));
    return 0;
}