#include <iostream>
#include <fstream>

using namespace std;

ifstream f("nrtri.in");
ofstream g("nrtri.out");

int n,v[801],i,s=0,c=0,j,mn,mx;

int main()
{
    f>>n;
    for(i=1;i<=n;i++)
        f>>v[i];
if(v[1]<v[2])
            mn=v[1],mx=v[2];
            else
            mn=v[2],mx=v[1];
        s=s+v[1]+v[2];

        for(i=3;i<=n;i++)
            if(v[i]+mn>=mx&&mn+mx>=v[i])
                c++/*,cout<<i<<" "<<v[i]<<mn*/;


    for(i=2;i<n;i++)
      {
          if(v[i]<v[i+1])
            mn=v[i],mx=v[i+1];
            else
            mn=v[i+1],mx=v[i];

        s=v[i]+v[i+1];

        for(j=i+2;j<=n;j++)
            if(v[j]+mn>=mx&&mn+mx>=v[j])
            c++;
      }
      g<<c;
}