package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func configure(scanner *bufio.Scanner) {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	n := getNextInt(scanner)
	sol := solver{}
	sol.aa = make([]int, n)
	for i := 0; i < n; i++ {
		sol.aa[i] = getNextInt(scanner)
	}
	g := newGrouping(n)
	g.dfs(0, 2, n, sol.calc)
	fmt.Fprintln(writer, sol.ans)
}

type solver struct {
	aa  []int
	ans int
}

func (s *solver) calc(g grouping) {
	n := len(g)
	aa := make([]int, n>>1)
	for i := 0; i < n; i++ {
		aa[g[i]] += s.aa[i]
	}
	var a int
	for i := 0; i < n>>1; i++ {
		a ^= aa[i]
	}
	if s.ans < a {
		s.ans = a
	}
}

type grouping []int

func newGrouping(n int) grouping {
	g := make(grouping, n)
	for i := 0; i < n; i++ {
		g[i] = -1
	}
	return g
}
func (g grouping) dfs(c, p, n int, fn func(grouping)) {
	if c == n {
		fn(g)
		return
	}
	if c%p == 0 {
		f := g.first()
		g[f] = c / p
		g.dfs(c+1, p, n, fn)
		g[f] = -1
		return
	}
	for i := g.last(c/p) + 1; i < n; i++ {
		if g[i] == -1 {
			g[i] = c / p
			g.dfs(c+1, p, n, fn)
			g[i] = -1
		}
	}
}
func (g grouping) first() int {
	n := len(g)
	for i := 0; i < n; i++ {
		if g[i] == -1 {
			return i
		}
	}
	return n
}
func (g grouping) last(a int) int {
	n := len(g)
	for i := n - 1; i >= 0; i-- {
		if g[i] == a {
			return i
		}
	}
	return -1
}