#include <stdio.h>

int a[1024], n;

int main() {
  freopen("nrtri.in", "r", stdin);
  freopen("nrtri.out", "w", stdout);
  
  scanf("%d", &n);
  
  for (int i = 1; i <= n; ++i)
    scanf("%d", &a[i]);
    
  for (int i = 1; i <= n; ++i)
    for (int j = i + 1; j <= n; ++j)
    if (a[i] > a[j]) {
      a[i] ^= a[j] ^= a[i] ^= a[j];
    }

  int ret = 0;
    
  for (int i = 1; i <= n; ++i)
    for (int j = i + 1; j <= n; ++j) {
      //A = a[i]
      //B = a[j]
      //C = ?
      //A + B >= C
      //C >= B - A
      //C >= A - B
      //=> max(A-B, B-A) <= C <= A + B
      int A = a[i];
      int B = a[j];
      int lim = A - B;
      if (lim < B - A)
        lim = B - A;
      int Lim = A + B;
      
      int p = 0, P = 0;
      for (int k = 512; k > 0; k /= 2) {
        //asta trebuie sa fie mai mare sau egal decat lim
        if (((p^k) <= n) && (a[p^k] < lim))
          p ^= k;

        //asta trebuie sa fie mai mic sau egal decat Lim
        if (((P^k) <= n) && (a[P^k] <= Lim))
          P ^= k;
      }
      ++p;
      
      int interval = P - p + 1; // p , p + 1, p + 2 ... P
      
      if (p <= i && i <= P)
        --interval;
      if (p <= j && j <= P)
        --interval;
          
      if (interval > 0)
        ret += interval;
    }

  //COMB(3,2) = 3*2 / 1*2 = 3
    
  printf("%d\n", ret/3);
  
  return 0;
}