#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    ifstream fin("nrtri.in");
    ofstream fout("nrtri.out");
    int N,a[805],i,x,y,z,k=0;
    fin>>N;
    for(i=1;i<=N;i++)
        fin>>a[i];
        for(x=1;x<=N;x++)
            for(y=x+1;y<=N;y++)
            for(z=y+1;z<=N;z++)
            if(a[x]+a[y]>=a[z]&&a[x]+a[z]>=a[y]&&a[y]+a[z]>=a[x])
            k++;
        fout<<k;
}