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

int i,j,n,m,a[1001],k,nr=0;
bool cmp(int a,int b)
{
    return a<b;
}
int main()
{
    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,cmp);
    for(i=1;i<=n-2;++i)
    for(j=i+1;j<n;++j)
    for(k=j+1;k<=n;++k)
    if(a[i]+a[j]>=a[k]&&a[i]+a[k]>=a[j]&&a[j]+a[k]>=a[i])
    ++nr;
    g<<nr<<"\n";
    return 0;
}