563.cpp

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

int solve_slow(const std::vector<uint32_t>& a) {
    const int n = (int)a.size();
    uint32_t s = 0; for (auto it : a) s ^= it;
    for (int i = 0; i < n-1; ++i) {
        uint32_t b = 0;
        for (int j = i + 1; j < n; ++j) {
            uint32_t diff = a[j] - a[i];
            b ^= (diff | (diff - 1)) - diff;
        }
        s ^= b;
    }
    return (int)s;
}


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

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

    std::vector<uint32_t> a(n);

    for (auto& it : a) {
        int value; scanf("%d", &value);
        it = (uint32_t)value;
    }

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

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

    return 0;
}