#include <iostream> #include<vector> #include<algorithm> #include<string> #include<map> #include<set> #include<stack> #include<queue> #include<math.h> using namespace std; typedef long long ll; #define int long long #define double long double typedef vector<int> VI; typedef pair<int, int> pii; typedef vector<pii> VP; typedef vector<string> VS; typedef priority_queue<int> PQ; template<class T>bool chmax(T &a, const T &b) { if (a < b) { a = b; return 1; } return 0; } template<class T>bool chmin(T &a, const T &b) { if (b < a) { a = b; return 1; } return 0; } #define fore(i,a) for(auto &i:a) #define REP(i,n) for(int i=0;i<n;i++) #define eREP(i,n) for(int i=0;i<=n;i++) #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define eFOR(i,a,b) for(int i=(a);i<=(b);++i) #define SORT(c) sort((c).begin(),(c).end()) #define rSORT(c) sort((c).rbegin(),(c).rend()) #define LB(x,a) lower_bound((x).begin(),(x).end(),(a)) #define UB(x,a) upper_bound((x).begin(),(x).end(),(a)) #define INF 1000000000 #define LLINF 9223372036854775807 #define mod 1000000007 #define eps 1e-12 //priority_queue<int,vector<int>, greater<int> > q2; signed main() { cin.tie(0); ios::sync_with_stdio(false); int N; cin >> N; VI A(N); REP(i, N)cin >> A[i]; int ans = 0; int sum = 0; REP(i, N) { REP(j, N) { if (i == j)continue; int cnt = sum; cnt ^= A[i]; cnt ^= A[j]; chmax(ans, cnt); } } cout << ans << endl; return 0; }