#include <iostream>

using namespace std;

int main()
{
    int n,nr=0;
    in>>n;
    int v[n];
    for(int i=0;i<n;i++)
        in>>v[i];
    for (int i = 0; i < n; ++i){
        for (int j = i+1; j < n; ++j) {
            if (v[i] > v[j]) {
                int aux = v[i];
                v[i] = v[j];
                v[j] = aux;
            }
        }
    }

    for(int i=0;i<n;i++)
    {
        for(int j=i+1;j<n;j++)
        {
            ///inlocuieste cu cautarea binara
            for(int k=j+1;k<n;k++)
            {
                if(v[i]+v[j]>=v[k] && v[j]<=v[i] + v[k]){
                    nr++;
                }
            }
        }
    }
    out<<nr;
    return 0;
}