#include <bits/stdc++.h>   using namespace std;   const int V = 100100;   int l[V], r[V], a[V], ret, n;   int main() {     while (~scanf( %d , &n)) {       ret = 0;       for (int i = 1; i <= n; i++) scanf( %d , &a[i]);       for (int i = 1; i <= n; i++) l[i] = r[i] = i;       for (int i = 1; i <= n; i++) {         while (l[i] != 1 && a[l[i] - 1] < a[i]) l[i] = l[l[i] - 1];         if (l[i] != 1) ret = max(ret, a[i] ^ a[l[i] - 1]);       }       for (int i = n; i >= 1; i--) {         while (r[i] != n && a[r[i] + 1] < a[i]) r[i] = r[r[i] + 1];         if (r[i] != n) ret = max(ret, a[i] ^ a[r[i] + 1]);       }       printf( %d n , ret);     }   }   