#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<ll,ll>
#define F first9
#define S second
const int N = 100;
int grid[N][N][N];
vector<int> getBits(int n){
vector<int>bits;
int nn = n;
int b = 0;
while(nn){
if( nn%2 ) bits.push_back(b);
b++;
nn/=2;
}
//for(auto bit:bits) cout<<bit<<" ";
reverse(bits.begin(),bits.end());
if( bits.size() == 1 ){
vector<int>res;
for(int i=1;i<=n;i++){
res.push_back(i);
}
return res;
}
int retN = 0;
for(int i=1;i<bits.size();i++)
retN+= (1<<bits[i]);
auto ret = getBits(retN);
int sz = ret.size();
int offset = 1<<bits[0];
for(int i=0;i<sz;i++)
ret.push_back( ret[i]+offset );
return ret;
}
int main(){
int n;
cin>>n;
int ara[n];
for(int i=0;i<n;i++) cin>>ara[i];
auto bits = getBits(n);
int xorr = 0;
for(auto bit:bits){
xorr^=ara[bit-1];
}
cout<<xorr;
}