class SegTree:

  def __init__(self, N, id, f):
    self.n = 2**(N-1).bit_length()
    self.unitX = id
    self.X = [id] * (self.n * 2)
    self.f = f
    self.N = N

  def update(self, i, x):
    i += self.n
    self.X[i] = x
    i >>= 1
    while i:
      self.X[i] = self.f(self.X[i*2], self.X[i*2|1])
      i >>= 1

  def getvalue(self, i):
    return self.X[i + self.n]

  def query(self, l, r):
    l += self.n
    r += self.n
    al = self.unitX
    ar = self.unitX
    while l < r:
      if l & 1:
        al = self.f(al, self.X[l])
        l += 1
      if r & 1:
        r -= 1
        ar = self.f(self.X[r], ar)
      l >>= 1
      r >>= 1
    return self.f(al, ar)

  def max_right(self, l, g):
    l += self.n
    ll = l // (l & -l)
    ans = self.unitX
    while g(self.f(ans, self.X[ll])):
      ans = self.f(ans, self.X[ll])
      ll += 1
      while ~ll & 1:
        ll >>= 1
      if ll == 1:
        return self.N
    while ll < self.n:
      ll <<= 1
      if g(self.f(ans, self.X[ll])):
        ans = self.f(ans, self.X[ll])
        ll += 1
    return ll-self.n
  
  def min_left(self, r, g):
    r += self.n
    rr = max(r // (~r & -~r), 1)
    ans = self.unitX
    while g(self.f(self.X[rr], ans)):
      ans = self.f(self.X[rr], ans)
      rr -= 1
      while rr & 1:
        rr >>= 1
      if rr == 0:
        return -1
    while rr < self.n:
      rr <<= 1
      if g(self.f(self.X[rr+1], ans)):
        ans = self.f(self.X[rr+1], ans)
      else:
        rr += 1
    return rr - self.n

def f(a,b):
  am1,am2,aM=a
  bm1,bm2,bM=b
  if am1<bm1:
    m1=am1
    m2=min(am2,bm1)
  else:
    m1=bm1
    m2=min(bm2,am1)
  M=max(aM,bM)
  return (m1,m2,M)

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

seg=SegTree(n,(10**18,10**18,-10**18),f)
for i in range(n):
  seg.update(i,(a[i],10**18,a[i]))

ans=0
for i in range(n-1):
  j=seg.max_right(i,lambda x:x[2]<=x[0]+x[1])
  ans+=j-i-1
print(ans)