Bike loves looking for the second maximum element in the sequence. The second maximum element in the sequence of distinct numbers x1, x2, ..., xk (k > 1) is such maximum element xj, that the following inequality holds: <image>.

The lucky number of the sequence of distinct positive integers x1, x2, ..., xk (k > 1) is the number that is equal to the bitwise excluding OR of the maximum element of the sequence and the second maximum element of the sequence.

You've got a sequence of distinct positive integers s1, s2, ..., sn (n > 1). Let's denote sequence sl, sl + 1, ..., sr as s[l..r] (1 ≤ l < r ≤ n). Your task is to find the maximum number among all lucky numbers of sequences s[l..r].

Note that as all numbers in sequence s are distinct, all the given definitions make sence.

Input

The first line contains integer n (1 < n ≤ 105). The second line contains n distinct integers s1, s2, ..., sn (1 ≤ si ≤ 109).

Output

Print a single integer — the maximum lucky number among all lucky numbers of sequences s[l..r].

Examples

Input

5
5 2 1 4 3


Output

7


Input

5
9 8 3 5 7


Output

15

Note

For the first sample you can choose s[4..5] = {4, 3} and its lucky number is (4 xor 3) = 7. You can also choose s[1..2].

For the second sample you must choose s[2..5] = {8, 3, 5, 7}.
#include <bits/stdc++.h>
using namespace std;
template <class T, class first>
inline bool getbit(T a, first i) {
  T t = 1;
  return ((a & (t << i)) > 0);
}
template <class T, class first>
inline T setbit(T a, first i) {
  T t = 1;
  return (a | (t << i));
}
template <class T, class first>
inline T resetbit(T a, first i) {
  T t = 1;
  return (a & (~(t << i)));
}
template <class T, class first>
inline T togglebit(T a, first i) {
  T t = 1;
  return (a ^ (t << i));
}
template <typename T>
T POW(T B, T P) {
  if (P == 0) return 1;
  if (P & 1)
    return B * POW(B, P - 1);
  else
    return (POW(B, P / 2) * POW(B, P / 2));
}
template <typename T>
T BIGMOD(T b, T p, T m) {
  if (p == 0)
    return 1;
  else if (!(p & 1))
    return (Bigmod(b, p / 2, m) * Bigmod(b, p / 2, m)) % m;
  else
    return ((b % m) * Bigmod(b, p - 1, m)) % m;
}
template <typename T>
T Bigmod(T base, T power, T mod) {
  T ret = 1;
  while (power) {
    if (power & 1) ret = (ret * base) % mod;
    base = (base * base) % mod;
    power >>= 1;
  }
  return ret;
}
template <typename T>
T ModInverse(T number, T mod) {
  return Bigmod(number, mod - 2, mod);
}
template <typename T>
T GCD(T a, T b) {
  if (a < 0) return gcd(-a, b);
  if (b < 0) return gcd(a, -b);
  return (b == 0) ? a : gcd(b, a % b);
}
template <typename T>
T LCM(T a, T b) {
  if (a < 0) return lcm(-a, b);
  if (b < 0) return lcm(a, -b);
  return a * (b / gcd(a, b));
}
template <typename T>
T EUCLIDE(T a, T b, T &x, T &y) {
  if (a < 0) {
    T d = euclide(-a, b, x, y);
    x = -x;
    return d;
  }
  if (b < 0) {
    T d = euclide(a, -b, x, y);
    y = -y;
    return d;
  }
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  } else {
    T d = euclide(b, a % b, x, y);
    T t = x;
    x = y;
    y = t - (a / b) * y;
    return d;
  }
}
template <typename T>
T ABS(T a) {
  if (a < 0)
    return -a;
  else
    return a;
}
double DEG(double x) { return (180.0 * x) / ((2.0 * acos(0.0))); }
double RAD(double x) { return (x * (double)(2.0 * acos(0.0))) / (180.0); }
template <typename T>
T DIS(T x1, T y1, T x2, T y2) {
  return sqrt((double)((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)));
}
template <typename T>
T ANGLE(T x1, T y1, T x2, T y2) {
  return atan(double(y1 - y2) / double(x1 - x2));
}
template <typename T>
long long isLeft(T a, T b, T c) {
  return (c.x - a.x) * (b.y - a.y) - (b.x - a.x) * (c.y - a.y);
}
void P_ARR(int *ar, int a, int b) {
  if (a > b) swap(a, b);
  if (a <= b) cout << ar[a];
  for (int i = a + 1; i <= b; i++) cout << " " << ar[i];
  cout << endl;
}
int tree[4 * 100007];
int ar[100007];
void build(int idx, int s, int e) {
  if (s == e) {
    tree[idx] = ar[s];
    return;
  }
  int mid = (s + e) >> 1, l = (idx << 1), r = (l | 1);
  build(l, s, mid);
  build(r, mid + 1, e);
  tree[idx] = max(tree[l], tree[r]);
}
int pos;
int flag;
void query(int idx, int s, int e, int x, int y, int v) {
  if (s > e) return;
  if (tree[idx] <= v) return;
  int mid = (s + e) >> 1, l = (idx << 1), r = (l | 1);
  if (s == x && e == y) {
    if (s == e) {
      if (flag)
        pos = min(pos, s);
      else
        pos = max(pos, s);
    } else {
      if (flag) {
        if (tree[l] > v)
          query(l, s, mid, s, mid, v);
        else
          query(r, mid + 1, e, mid + 1, e, v);
      } else {
        if (tree[r] > v)
          query(r, mid + 1, e, mid + 1, e, v);
        else
          query(l, s, mid, s, mid, v);
      }
    }
    return;
  }
  if (y <= mid)
    query(l, s, mid, x, y, v);
  else if (x > mid)
    query(r, mid + 1, e, x, y, v);
  else {
    query(l, s, mid, x, mid, v);
    query(r, mid + 1, e, mid + 1, y, v);
  }
}
int main() {
  int(n);
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &(ar[i]));
  build(1, 1, n);
  int res = 0;
  for (int i = 1; i <= n; i++) {
    flag = 1;
    pos = 1000000000;
    query(1, 1, n, i + 1, n, ar[i]);
    if (pos != 1000000000) res = max(res, ar[i] ^ ar[pos]);
    flag = 0;
    pos = -1;
    query(1, 1, n, 1, i - 1, ar[i]);
    if (pos != -1) res = max(res, ar[i] ^ ar[pos]);
  }
  cout << res << endl;
  return 0;
}
