#include<iostream>
#include<fstream>
#include<algorithm>
using namespace std;
int a[1000];
int main()
{int n,i,j,h,k=0;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
f>>n;
for(i=1;i<=n;i++)f>>a[i];
sort(a+1,a+n+1);
for(i=1;i<=n;i++)
    for(j=i+1;j<=n;j++)
        for(h=j+1;h<=n;h++)
            if((a[i]+a[j]>=a[h]) && (a[j]+a[h]>=a[i]) && (a[h]+a[i]>=a[j]))k++;
            else break;

g<<k;}