#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#define ll long long
#define fori(i,j,k) for(ll i=j; i<=k;i++)
#define study ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define pb push_back
#define all(s) s.begin(),s.end()
#define ins insert
#define ss second
#define ff first
const ll sz=1e3+10;
ll INF=1e12;
ll mod=1e9+7;
void work(){
ll n;
cin>>n;
vector<ll>v(n+10,0);
fori(i,1,n)
cin>>v[i];
ll ans=0;
fori(i,1,n){
fori(j,i,n){
ans^=(v[i]+v[j]);
}
}
cout<<ans;
}
int main()
{
// #ifndef LOCAL
// freopen("maxcross.in","r",stdin);
// freopen("maxcross.out","w",stdout);
// #endif
study;
ll t=1;
//cin>>t;
fori(i,1,t)
work();
}
/*
abca
acba
aca
aba
aa
abbacca
accabba
*/
