未开发

using namespace std;
typedef long long ll;
const int N = 110, len = 32;
bool vis[N];
ll a[N], b[N];
int n;

bool insert(ll x)	
{
	for(int j = len; j >= 0; --j)	
	{
		if((x & (1ll << j))== 0)
			continue;
		if(b[j])		
			x ^= b[j];	
		else{

			for(int k = j - 1; k >= 0; --k)
			{
				if(x & (1ll << k))
					x ^= b[k];
			}
 
			for(int k = len; k >= j + 1; --k)
			{
				if(b[k] & (1ll << j))
					b[k] ^= x;
			}
			b[j] = x;	
			return true;	
		}						
	}	
	return false;
}

int main()
{
	scanf("%d", &n);
	for(int i = 0; i < n; ++i)
		scanf("%lld", &a[i]);
	sort(a, a + n, greater<int>());
	int cnt = 0;	
	ll sum = 0;		
	for(int i = 0; i < n; ++i)
	{
		if(insert(a[i]))
			vis[i] = true, cnt++;
		else
			sum += a[i];
	}
	if(cnt == 1)
		printf("-1\n");	
	else
		printf("%lld\n", sum);
	return 0;
}