#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define ll long long
#define str string
#define pb push_back
#define pf push_front
#define in insert
#define all(v) v.begin(),v.end()
#define fastIO ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
const int sz=1000001,INF=1000000000;
using namespace std;
void solve()
{
ll n,num,ans=0;
cin>>n;
vector<ll>nums,counts(sz,0),cnts(sz,0);
set<ll>Nums;
for(int i=0;i<n;i++)
{
cin>>num;
Nums.in(num),counts[num]++;
}
for(auto Num:Nums)
{
nums.pb(Num);
}
for(int i=0;i<nums.size();i++)
{
for(int j=i;j<nums.size();j++)
{
cnts[nums[i]+nums[j]]+=counts[nums[i]]*counts[nums[j]];
}
cnts[2*nums[i]]+=counts[nums[i]]*(counts[nums[i]]-1)/2;
}
for(int i=1;i<sz;i++)
{
if(cnts[i]!=0 && cnts[i]%2!=0)
{
ans^=i;
}
}
cout<<ans;
}
int main()
{
fastIO;
ll t=1;
//cin>>t;
while(t--)
{
solve();
}
}
