#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <cstring>
#include <math.h>
#include <bitset>
#include <queue>
#include <set>
#include <iomanip>
#include <math.h>
#include <assert.h>
// #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
constexpr long long int INFLL = 1001001001001001LL;
constexpr long long int infll = 1001001001001001LL;
constexpr int INF = 1000000007;
constexpr int inf = 1000000007;
const int mod = 1000000007;

template <class T>
inline bool chmin(T &a, T b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}

ll gcd(ll a, ll b)
{
    if (a % b == 0)
    {
        return (b);
    }
    else
    {
        return (gcd(b, a % b));
    }
}

ll lcm(ll a, ll b)
{
    return a / gcd(a, b) * b;
}

template <typename T>
T seinomi(T a)
{
    if (a > 0)
    {
        return a;
    }
    else
    {
        return 0;
    }
}

template <typename T>
map<T, T> soinsuubunkai(T n) //連想配列[素因数f.first][個数f.second]
{
    map<T, T> ret;
    for (T i = 2; i * i <= n; i++)
    {
        while (n % i == 0)
        {
            ret[i]++;
            n /= i;
        }
    }
    if (n != 1)
        ret[n] = 1;
    return ret;
}

template <typename T>
T ketasuu(T num)
{
    return std::to_string(num).length();
}

int kaizyou(int k)
{
    int sum = 1;
    for (int i = 1; i <= k; ++i)
    {
        sum *= i;
    }
    return sum;
}

ll modkaizyou(ll k)
{
    ll sum = 1;
    for (int i = 1; i <= k; ++i)
    {
        sum *= i;
        sum = sum % mod;
    }
    return sum;
}

template <class ForwardIt, class T>
void iota(ForwardIt first, ForwardIt last, T value)
{
    while (first != last)
    {
        *first++ = value;
        ++value;
    }
}

//整数乗
int llpow(ll a, ll n)
{ //aのn乗を計算します。
    ll x = 1;
    while (n > 0)
    { //全てのbitが捨てられるまで。
        if (n & 1)
        { //1番右のbitが1のとき。
            x = x * a;
        }
        a = a * a;
        n >>= 1; //bit全体を右に1つシフトして一番右を捨てる。
    }
    return x;
}

long long modpow(long long a, long long n, long long mod)
{
    long long res = 1;
    while (n > 0)
    {
        if (n & 1)
            res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

template <typename T>
T amarinasi(T a, T b)
{
    if (a % b == 0)
    {
        return a / b;
    }
    else if (a % b > 0)
    {
        return a / b + 1;
    }
    else
    {
        return a / b - 1;
    }
}

//組み合わせ nCr
void nCr_Calculater(vector<vector<long long int>> &v)
{
    for (int i = 0; i < v.size(); i++)
    {
        v[i][0] = 1;
        v[i][i] = 1;
    }
    for (int k = 1; k < v.size(); k++)
    {
        for (int j = 1; j < k; j++)
        {
            v[k][j] = (v[k - 1][j - 1] + v[k - 1][j]);
        }
    }
}
ll nCr(ll N, ll K)
{
    vector<vector<long long int>> v(N + 1, vector<long long int>(N + 1, 0));
    nCr_Calculater(v);
    return v[N][K];
}

// 組み合わせnCrを1000000007で割った余り
void COMinit(vector<ll> &fac, vector<ll> &finv, vector<ll> &inv)
{
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < 1000010; i++)
    {
        fac[i] = fac[i - 1] * i % mod;
        inv[i] = mod - inv[mod % i] * (mod / i) % mod;
        finv[i] = finv[i - 1] * inv[i] % mod;
    }
}
long long COM(int n, int k, vector<ll> &fac, vector<ll> &finv, vector<ll> &inv)
{
    if (n < k)
        return 0;
    if (n < 0 || k < 0)
        return 0;
    return fac[n] * (finv[k] * finv[n - k] % mod) % mod;
}
ll modnCr(ll n, ll r)
{
    vector<ll> fac(1000010), finv(1000010), inv(1000010);
    COMinit(fac, finv, inv);
    return COM(n, r, fac, finv, inv);
}

//順列　nPr
ll nPr(ll n, ll r)
{
    r = n - r;
    ll sum = 1;
    ll i;
    for (i = n; i >= r + 1; i--)
        sum *= i;
    return sum;
}

//重複組み合わせ　nHr = (r+n-1)Cr
ll nHr(ll n, ll r)
{
    return nCr(r + n - 1, r);
}

//弧度法から度数法に変換
double to_deg(double r)
{
    return r * 180.0 / (atan(1.0) * 4.0);
}

//座標から度数法の角度に変換
double kakudo(double dx, double dy)
{
    return atan2(dx, dy) * 180.0 / (atan(1.0) * 4.0);
}

//小数点以下10桁テンプレート（main関数内の最初に貼付け）
//std::cout << std::fixed << std::setprecision(10);

//----------------------------------------------------------------

int main()
{
    ll n;
    cin >> n;
    ll l[n];
    for (ll i = 0; i < n; i++)
    {
        cin >> l[i];
        l[i] = l[i];
    }
    sort(l, l + n);
    ll sum = 0;

    for (ll i = 0; i < n - 1; i++)
    {
        for (ll j = i + 1; j < n; j++)
        {
            ll tmp = l[j] - l[i];
            auto itr = upper_bound(l, l + n, tmp);
            sum += seinomi(l + i - itr);
        }
    }
    cout << sum << endl;
}

Measured memory_bytes: 256