#include <bits/stdc++.h>
#define ll long long
#define endll '\n';
#define pb push_back
#define all(v) v.begin(), v.end()
using namespace std;


const int mod = 1e9 + 7, N = 1e6;
int dp[N];
int rec(int x) {
    if(x < 0) return 1e5;
    if(x == 0) return 0;
    if(dp[ x] != -1) return dp[x];
    int ans = 1e9;
    ans = min(ans, rec(x - 2) + 1);
    ans = min(ans, rec(x - 3) + 1);
    return dp[x] = ans;
}
void solve()
{
  int n; cin >> n;
  int xr = 0;
  for(int i = 1; i <= n; i++) {
    int x; cin >> x;
    xr ^= x;
  }
  cout << xr << endll;
}

int32_t main()
{
  ios::sync_with_stdio(false);
  cin.tie(0);
  int t = 1;
  for(int  i = 0; i <= 200; i++) dp[i] = -1;
//   cin >> t;
  while (t--) {
    solve();
}
 return 0;
}