龚体诗记录：）。

你出卖灵魂有保障

母亲买保险

甩甩脑袋又去上班

结局皆大欢喜

---

脑子上的包 非常地大

---

那日回头望

楼上房间看到了

向前看

竟是脑子上的包

---

牛逼一二大于我

做好翻译为民

至今未见位于韩国

谷歌科技有限公司

---

宗教事务管理附件

附近医院放假一天

无脑文件发生的我

无颜面对眼也笑了

---

解决方法显而易见

---

要发生了

感觉一无是处

朋友突然飞机化

解决方法显而易见

https://darkbzoj.tk/problem/4176

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define cmin(x, ...) x = min({x, __VA_ARGS__})
#define cmax(x, ...) x = max({x, __VA_ARGS__})
#define fors(i, l, r, ...) for(int i = (l), i##end = (r), ##__VA_ARGS__; i <= i##end; i++)
#define dfors(i, r, l, ...) for(int i = (r), i##end = (l), ##__VA_ARGS__; i >= i##end; i--)
const int P = 1000000007;
// f = mu, g = 1, f*g = e
// g(1)S(n) = (sum(1~n)f*g[i])-(sum(2~n)g[i]*S(n/i))
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x^(x>>30))*0xbf58476d1ce4e5b9;
        x = (x^(x>>27))*0x94d049bb133111eb;
        return x^(x>>31);
    }
    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x+FIXED_RANDOM);
    }
};
const function<int(const int)> p_mu = [](const int x) {
    static const int THRESHOLD = 1e7;
    static unordered_map<int, int, custom_hash> g_mu;
    static const auto l_mu = [](const int n) {
        vector<int> mu(n+1), prime;
        vector<bool> not_prime(n+1);
        fors(i, (mu[1] = 1)+1, n) {
            if(not_prime[i] == 0) mu[i] = P-1,prime.emplace_back(i);
            for(const int p : prime) {
                if(i > n/p) break;
                not_prime[i*p] = 1;
                if(i%p == 0) break;
                mu[i*p] = P-mu[i];
            }
        }
        fors(i, 1, n) mu[i] += mu[i-1],mu[i] %= P;
        return mu;
    }(THRESHOLD);
    if(x <= THRESHOLD) return l_mu[x];
    if(g_mu.count(x)) return g_mu[x];
    int res = 1; // sum of e(n)
    for(int l = 2, r; l <= x; l = r+1) {
        r = x/(x/l);
        res -= ll(r-l+1)*p_mu(x/l)%P, res %= P;
    }
    return g_mu[x] = (res+P)%P;
};
const auto rg_mu = [](const int l, const int r) { return (p_mu(r)-p_mu(l-1)+P)%P; };
int p_div_sum(const int n) { // return (sum(1~n) n/i)^2
    int res = 0;
    for(int l = 1, r; l <= n; l = r+1) {
        r = n/(n/l);
        res += ll(n/l)*(r-l+1)%P, res %= P;
    }
    return ll(res)*res%P;
}
signed main() {
    ios::sync_with_stdio(0), cin.tie(0);
    int n, ans = 0;
    cin >> n;
    for(int l = 1, r; l <= n; l = r+1) {
        r = n/(n/l);
        ans += (ll)rg_mu(l, r)*p_div_sum(n/l)%P, ans %= P;
    }
    cout << ans << "\n";
    return 0;
}

quote lyrics from laur

This is the story of an ordinary man

He's a quiet man who seeks no glory,

but he's not afraid to defend what he loves

He is a simple man

who knows only that loyalty, honesty, and truth mean everything

This is the story of a hero

She is the last of her kind,

the descendant of an ancient line of women

who commanded reverence, obedience, and love

But only when he faces

the dark secret within his own heart, can he grow to the man

who has been chosen?

I think there's a reason I'm a shadow, but she looks like an angel

What's your name pretty boy?

Which way do you think we should go?

Her shadow, an endless night, falls on the land

One man must undertake an expedition, an ancient treasure

But the fire that brings the light can also burn the soul

The only companion that you can trust is courage