#include <bits/stdc++.h>
using namespace std;
template<typename TH>
void _dbg(const char* sdbg, TH h)
{
cerr << sdbg << " = " << h << "\n";
}
template<typename TH, typename... TA>
void _dbg(const char* sdbg, TH h, TA... t)
{
while (*sdbg != ',') cerr << *sdbg++;
cerr << " = " << h << ",";
_dbg(sdbg + 1, t...);
}
#define db(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#define chkpt cerr << "--- Checkpoint here ---\n";
const int N=1e6+6;
int n,a[N];
void Sub1(){
int ans=0;
for(int i=1;i<=n;++i){
for(int j=i;j<=n;++j){
ans^=(a[i]+a[j]);
}
}
cout<<ans;
}
int main()
{
// freopen("info1cup17_xorsum.inp","r",stdin);
ios_base::sync_with_stdio(0);
cin.tie(0);
cin>>n;
for(int i=1;i<=n;++i){
cin>>a[i];
}
Sub1();
return 0;
}
