#include <iostream>
#include <fstream>
#include <cstring>
#include <string>
#include <climits>
using namespace std;
ifstream fin ("nrtri.in");
ofstream fout("nrtri.out");

#define MAX 32768

int n,A,B,a[MAX],i,j,b[MAX];

int BS(int start, int end, int x)
{
    int mid;
    if(a[end]<=x)
        return end;
    if(a[start]>x)
        return start-1;
    while(start<=end)
    {
        mid=start+(end-start)/2;
        if(a[mid]<x && x<a[mid+1])
        {
            return mid;
        }
        else if(a[mid]==x && a[mid+1]!=x)
        {
            return mid;
        }
        else if(a[mid]==x)
        {
            start=mid+1;
        }
        else if(x<a[mid])
        {
            end=mid-1;
        }
        else
        {
            start=mid+1;
        }
    }
    return start-1;
}

void sort()
{
    int ok,k=0;
    do
    {
        ok=1;
        for(i=1;i<n-k;i++)
        {
            if(a[i]>a[i+1])
            {
                int t=a[i];
                a[i]=a[i+1];
                a[i+1]=t;
                ok=0;
            }
        }
        k++;
    }while(!ok);
}


int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
    {
        fin>>a[i];
    }
    sort();
    int count=0;
    for(i=1;i<n-1;i++)
    {
        for(j=i+1;j<n && a[i]+a[j]>=a[j+1];j++)
        {
            count+=BS(j,n,a[i]+a[j])-j;
        }
    }
    fout<<count;
    return 0;
}

/*
#include <iostream>
#include <fstream>
#include <cstring>
#include <string>
#include <climits>
using namespace std;
ifstream fin ("teams.in");
ofstream fout("teams.out");

#define MAX 32768

int n,A,B,a[MAX],i,j,b[MAX];

int BS(int start, int end, int x)
{
    int mid;
    if(a[end]<=x)
        return end;
    if(a[start]>x)
        return start-1;
    while(start<=end)
    {
        mid=start+(end-start)/2;
        if(a[mid]<x && x<a[mid+1])
        {
            return mid;
        }
        else if(a[mid]==x && a[mid+1]!=x)
        {
            return mid;
        }
        else if(a[mid]==x)
        {
            start=mid+1;
        }
        else if(x<a[mid])
        {
            end=mid-1;
        }
        else
        {
            start=mid+1;
        }
    }
    return start-1;
}

void loop()
{

    int k=0;
    for(i=0; i<=MAX && k<=n; i++)
    {
        while(b[i]>0)
        {
            k++;
            a[k]=i;
            b[i]--;
        }
    }
    cout<<INT_MAX;
}

int main()
{
    fin>>n>>A>>B;
    a[0]=INT_MIN;
    a[n+1]=INT_MAX;
    for(i=1;i<=n;i++)
    {
        fin>>j;
        b[j]++;

    }
    loop();

    int count=0;

    for(i=1;i<=n;i++)
    {
        count=count+(BS(i+1,n,B-a[i])-BS(i+1,n,A-i-1));
     //   cout<<BS(i+1,n,B-a[i])<<"-"<<BS(i+1,n,A-i-1)<<"="<<(BS(i+1,n,B-a[i])-BS(i+1,n,A-i-1))<<"\n";
        if((a[i]+a[i+1])>B)
            break;
    }
    fout<<count;
   // cout<<count;
}
*/