#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("nrtri.in");
ofstream fout("nrtri.out");

int n,i,a[805],N,b[805],Nr,j,k;

void Read()
{
    fin>>n;
    for(i=1;i<=n;i++)
    fin>>a[i];
}
int Form(int x, int y, int z)
{
      return ( (x<=y+z)&& (y<=x+z) && (z<=x+y));
}
void SolveandPrint()
{
    sort(a+1,a+1+n);
    for(i=1;i<=n;i++)
        for(j=i+1;j<=n;j++)
            for(k=j+1;k<=n;k++)
        if(Form(a[i],a[j],a[k]))
        Nr++;
        fout<<Nr;
}
int main()
{
    Read();
    SolveandPrint();
}