算式子

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 2e6 + 10;

ll ans1[N], ans2[N], cnt[N], sum[N];

int n, m;

void init() {
  for (int i = 1; i <= m; i++) {
    for (int j = i; j <= m; j += i) {
      int r = min(j + i - 1, m), l = j;
      ans1[i] += 1ll * (cnt[r] - cnt[l - 1]) * (j / i);
      ll res = 1ll * (j / i) * (cnt[i] - cnt[i - 1]);
      ans2[l] += res;
      ans2[r + 1] -= res;
    }
  }
  for (int i = 1; i <= m; i++) {
    ans2[i] += ans2[i - 1];
  }
}

int main() {
  // freopen("in.txt", "r", stdin);
  // freopen("out.txt", "w", stdout);
  // ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= n; i++) {
    int x;
    scanf("%d", &x);
    cnt[x]++;
  }
  for (int i = 1; i <= m; i++) {
    cnt[i] += cnt[i - 1];
  }
  init();
  ll ans = 0;
  for (int i = 1; i <= m; i++) {
    ans ^= (ans1[i] + ans2[i]);
  }
  printf("%lld\n", ans);
  return 0;
}