563.cpp

#include <stdio.h>
#include <vector>
#include <cmath>
#include <cassert>
#include <algorithm>

int solve_slow(const std::vector<int>& a) {
    const int n = (int)a.size();
    int s = 0; for (auto it : a) s ^= it;
    for (int i = 0; i < n-1; ++i) {
        int b = 0;
        for (int j = i + 1; j < n; ++j) {
            int diff = a[j] - a[i];
            b ^= (diff | (diff - 1)) - diff;
        }
        s ^= b;
    }
    return s;
}


int main() {
    freopen("input.txt", "rt", stdin);

    int n;
    scanf("%d", &n);

    std::vector<int> a(n); for (auto& it : a) scanf("%d", &it);

    std::sort(a.begin(), a.end());

    printf("%d", solve_slow(a));

    return 0;
}