n = int(input())
a = list(map(int, input().split()))

t = 1

ans = 0
l = 0
while l < n-1:
  M = sorted(a[l:l+t+1])[-1]
  m1 = sorted(a[l:l+t+1])[0]
  m2 = sorted(a[l:l+t+1])[1]
  while l + t+1 <= n-1:
    t += 1
    x = M
    y = m1
    z = m2
    if a[l+t] > x:
      M = a[l+t]
    if y <= a[l+t] <= z:
      m2 = a[l+t]
    if a[l+t] < y:
      m2 = y
      m1 = a[l+t]
    if M <= m1 + m2:
      continue
    if M > m1 + m2:
      break
  if l + t == n-1:
    ans += t
    l += 1
    t -= 1
  else:
    ans += t -1
    l += 1
    if t-1 == 1:
      t = 1
    else:
      t = t -2


print(ans)