#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

vector<int> match;

int findLast(int index, int right, int firstPick, int secondPick) {
    while (index <= right && match[index] <= match[firstPick] + match[secondPick]
           && match[firstPick] <= match[index] + match[secondPick] && match[secondPick] <= match[index] + match[firstPick]) {
                index++;
           }

    return index - 1;
}

int binarySearch(int left, int right, int firstPick, int secondPick) {
    int mid, nrSol = 0;

    while (left <= right) {
        mid = left + ((right - left) >> 1);
        if (mid > secondPick && match[mid] <= match[firstPick] + match[secondPick]
            && match[firstPick] <= match[mid] + match[secondPick] && match[secondPick] <= match[mid] + match[firstPick]) {
                mid = findLast(mid + 1, right, firstPick, secondPick);
                /*for (mid; mid <= right; ++mid) {
                    if (match[mid] <= firstPick + secondPick && firstPick <= match[mid] + secondPick
                        && secondPick <= match[mid] + firstPick)
                            nrSol++;
                    }*/
                return mid;
        }
        else left = mid + 1;
    }

    return secondPick;
}

int main() {
    int noOfMatches;

    ifstream in("nrtri.in");
    in >> noOfMatches;
    // Citire vector
    for (int i = 0; i < noOfMatches; ++i) {
        int lenOfMatch;
        in >> lenOfMatch;
        match.push_back(lenOfMatch);
    }
    in.close();
    //Sortare vector
    sort(match.begin(), match.end());
    int nrSol = 0;
    for (int i = 0; i < noOfMatches - 1; ++i) {
        for (int j = i + 1; j < noOfMatches; ++j) {
            nrSol += binarySearch(0, noOfMatches - 1, i, j) - j;
        }
    }

    ofstream out("nrtri.out");
    out << nrSol << '\n';
    out.close();

    return 0;
}