#include <iostream>
#include <fstream>
using namespace std;
int n;
unsigned a[200],b[200],c[200];
void citire()
{
    ifstream f ("nrtri.in");
    int i;
    f>>n;
    for(i=0;i<n;i++)
        {f>>a[i];
        b[i]=a[i];
        c[i]=a[i];
        }
    f.close();
}
int cautare()
{
    int i,k,j,s=0;
    for(i=0;i<n-2;i++)
        for(j=i+1;j<n-1;j++)
            for(k=j+1;k<n;k++)
                if((a[i]<=b[j]+c[k])&&(b[j]<=c[k]+a[i])&&(c[k]<=b[j]+a[i]))
                    s++;

return s;
}
int main()
{
    citire();
    ofstream g ("nrtri.out");
    g<<cautare();
    g.close();
    return 0;
}