e319 - 2

/* e319 - 2         */
/* AC (0.3s, 116KB) */
#pragma warning( disable : 4996 )
#include <cstdio>
#include <cstdint>
using namespace std;

using int16 = int_fast16_t;
using int32 = int_fast32_t;
using int64 = int_fast64_t;

/* main code */
int32 N, result = 0, a, b, c, x;

int main()
{
    scanf("%d", &N);
    a = b = c = 0;
    while (N-- && scanf("%d", &x))
    {
        c = x & b;
        b &= ~x;
        x &= ~c;
        b |= a & x;
        a ^= x;
    }
    printf("%d", a);

    return 0;
}