#include <iostream>
#include <fstream>

using namespace std; 
  
int ntri(int v[], int n) 
{ 

    int count = 0; 
  
    for (int i = 0; i < n; i++) { 
        for (int j = i + 1; j < n; j++) { 
            for (int k = j + 1; k < n; k++) 
  
                if ( 
                    v[i] + v[j] > v[k] 
                    && v[i] + v[k] > v[j] 
                    && v[k] + v[j] > v[i]) 
                    count++; 
        } 
    } 
    return count; 
} 
  
int main() 
{
    ifstream f("ntri.in");
    ofstream g("ntri.out");

    int n, v[1000]; 
    int i;

    f>>n;

    for(i=0; i<n; i++){
        f>>v[i];
    }

    g<<ntri(v, n);
  
    return 0; 
}