#include<iostream>
#include<fstream>
using namespace std;
int main()
{
    int i,n,j,d,contor=0,v[100],b[100],c[100];
    ifstream fin("nrtri.in");
    ofstream fout("nrtri.out");
    fin>>n;
    for(i=0;i<n;i++)
    {fin>>v[i];
    b[i]=v[i];
    v[i]=c[i];
           }
    for(i=0;i<n;i++)
    for(j=i+1;j<n-1;j++)
     for(d=j+1;d<n;d++)
     if((v[i]<=b[j]+c[d])&&(b[j]<=v[i]+c[d])&&(c[d]<=v[i]+b[j])) contor++;
     fout<<contor;
     return 0;
     }