#include <iostream> #include <map> using namespace std; int i, j, n, v[1000001], aux1, aux2; long long sum; map <int, int> mp; int main() { cin >> n; for ( i = 1; i <= n; i++ ) { cin >> v[i]; mp[v[i]]++; } if ( n < 1000001 ) { for ( i = 1; i <= n; i++ ) { for ( j = i; j <= n; j++ ) { aux1 = ( v[i]+v[j] ); sum = ( sum ^ aux1 ); } } cout << sum; } return 0; }