itmo_простая_задача_2

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int, int>
#define pb(x) push_back(x)
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}

void cvl(vector <ll> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}


void cvv(vector <vector <int> > &v) {
    for (auto x : v) cv(x);
    cout << "\n";
}

void cvb(vector <bool> v) {
    for (bool x : v) cout << x << ' ';
    cout << "\n";
}

void cvs(vector <string>  v) {
    for (auto a : v) {
        cout << a << "\n";
    }
}

void cvp(vector <pii> a) {
    for (auto p : a) {
        cout << p.first << ' ' << p.second << "\n";
    }
    cout << "\n";
}



int main() {
    /*ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);*/
    int n;
    cin >> n;
    bool sh = 0;
    vector <int> v(n);
    int til = 500;
    vector <ll> dp(600, 0);
    for (int &i: v) {
        cin >> i;
        dp[i]++;
    }
    ll ans = 0;


    vector <ll> pf(520, 0);
    for (ll i = 1; i <= til; ++i) {
        pf[i] = pf[i - 1] + dp[i];
    }
    if (sh) {
        cout << "pf\n";
        cvl(pf);
    }

    //pf - именно кол-вотаких-то чисел, а не сумма
    for (int a = 1; a <= til; ++a) {
        for (int b = 1; b <= til; ++b) {
            for (int c = 1; c <= til; ++c) {
                if (dp[a] == 0 || dp[b] == 0 || dp[c] == 0) {
                    continue;
                }
                ll fro = a * b / c;
                if (fro * c < a * b) fro++;
                if (fro > 500) {
                    continue;
                }
                ll del = 0;
                if (fro - 1 >= 0) {
                    del = pf[fro - 1];
                }
                ll Sd = pf[til] - del;
                ll plu = dp[a] * dp[b] * dp[c] * Sd;
                ans += plu;
                if (sh && plu > 0 && fro == 18) {
                    cout << "a b c = " << a << ' ' << b << ' ' << c << "\n";
                    cout << "fro = " << fro << "\n";
                    cout << "Sd = " << Sd << "\n";
                    cout << "plu = " << plu << "\n";
                    cout << "del = " << del << "\n";
                    cout << "\n\n";
                }
            }
        }
    }

    cout << ans;
}
/*
a b c = 6 6 2
fro = 18
Sd = 3
plu = 3
*/