#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;

void afis(int a[800], int n) {
    int i;
        for(i=0;i<n;i++) {
        cout << a[i] << " ";
    }
}

int main()
{
    int a[800],n,i;
    ifstream in("nrtri.in");
    ofstream out("nrtri.out");
    in >> n;
    for(i=0;i<n;i++) {
        in >> a[i];
    }
    sort(a,a+n);

    int j;
    int contor = 0;
    int maxim = 0 ;
    int suma = 0;
    for(i=0;i<=n-1;i++)
        for(j=i+1;j<=n-1;j++)
                    {
                        /*if (a[i]>=a[j]) {maxim = a[i];suma = suma + a[j]; }
                        else {maxim = a[j] ; suma = suma + a[i];}
                        if (maxim<= a[j+1]) {suma = suma + maxim ; maxim = a[j+1];}
                        else suma = suma + a[j+1] ;
*/

            suma = a[i] + a[j];
            maxim = a[j+1];
                        if (suma >= maxim ) contor++;
                    }
out<<contor;
    in.close();
    out.close();
    return 0;
}