ll a[maxn];
__int128 ans;
__int128 Mod=9223372036854775807;
int main() {
	++Mod;
	Mod*=2;
	read(n);
	for(int i(1);i<=n;++i)read(a[i]);
	ll lst_v=0;
	ll N=(1<<n);
	for(ll i(1);i<N;++i){
		ll num=(i^(i/2));
		int x=__builtin_ffs(i);
		//lst_num=num;
		lst_v^=a[x];
		ans^=((__int128)lst_v*num%Mod);
	}
	write(ans);
    return 0;
}