#include<bits/stdc++.h>
#define in f
#define out g
using namespace std;

ifstream f ("nrtri.in");
ofstream g ("nrtri.out");

int n;
int M[100];
int nr;

int main() {

    in >> n;
   for(int l = 1; l <= n; l++ )
   {
       in >> M[l];
   }
   for(int i = 1; i <= n; i++)
   {
       for (int j = i + 1; j <= n; j++)
       {
          for (int k = j + 1; k <= n; k++)
          {
              if(( M[i] + M[j] >= M[k] ) && ( M[i] + M[k] >= M[j]) && ( M[k] + M[j] >= M[i] ))
              {
                   nr=nr+1;
              }

          }
       }
   }
out << nr;
}