#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

int v[810];

bool comp(int a,int b){
return a<b;
}

int main()
{
    ifstream in("nrtri.in");
    ofstream out("nrtri.out");
    int n,i,j,k,cnt=0,suma=0;
    in>>n;
    for(i=1;i<=n;i++)
    {
        in>>v[i];
    }
    sort(v+1,v+n+1,comp);
    for(i=1;i<n;i++)
    {
        for(j=i+1;j<=n;j++)
        {
            suma=v[i]+v[j];
            for(k=j+1;k<=n;k++)
            {
                if(v[k]<=suma)
                {
                    cnt++;
                }
            }
        }
    }
    out<<cnt;
    return 0;
}