庭师的利刃

#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#include <deque>
#include <map>
#define range(i,a,b) for(int i=a;i<=b;++i)
#define LL long long
#define rerange(i,a,b) for(int i=a;i>=b;--i)
#define fill(arr,tmp) memset(arr,tmp,sizeof(arr))
using namespace std;
LL aa[1000005],ans;
int n;
void init(){
    cin>>n;
    range(i,1,n)cin>>aa[i];
}
void solve(){
    rerange(i,31,1) {
        int tmp = 0;
        range(j, 1, n)if (((ans & aa[j]) == ans) && (aa[j] & (1 << (i - 1))))++tmp;
        if (tmp >= 2)ans += (1 << (i - 1));
    }
    cout<<ans<<endl;
}
int main() {
    init();
    solve();
    return 0;
}