class SegmentTree:
  def __init__(self, n, p, unit, f):
    self.n = n
    self.num = 2**((n-1).bit_length())
    self.seg = [unit]*(self.num*2)
    for i in range(n):
      self.seg[self.num+i] = p[i]
    for i in range(self.num-1, 0, -1):
      self.seg[i] = f(self.seg[i << 1], self.seg[(i << 1)+1])
    self.unit = unit
    self.f = f

  def update(self, i, x):
    i += self.num
    self.seg[i] = x
    while i:
      i >>= 1
      self.seg[i] = self.f(self.seg[i << 1], self.seg[(i << 1)+1])

  def query(self, l, r):
    ansl = ansr = self.unit
    l += self.num
    r += self.num-1
    if l == r:
      return self.seg[l]
    while l < r:
      if l & 1:
        ansl = self.f(ansl, self.seg[l])
        l += 1
      if ~r & 1:
        ansr = self.f(self.seg[r], ansr)
        r -= 1
      l >>= 1
      r >>= 1
    if l == r:
      ansl = self.f(ansl, self.seg[l])
    return self.f(ansl, ansr)

  def max_right(self, l, g):
    l += self.num
    ll = l // (l & -l)
    ans = self.unit
    while g(self.f(ans, self.seg[ll])):
      ans = self.f(ans, self.seg[ll])
      ll += 1
      while ~ll & 1:
        ll >>= 1
      if ll == 1:
        return self.n
    while ll < self.num:
      ll <<= 1
      if g(self.f(ans, self.seg[ll])):
        ans = self.f(ans, self.seg[ll])
        ll += 1
    return ll-self.num

def f(x,y):
  xm1,xm2,xM=x
  ym1,ym2,yM=y
  if xm1<ym1:
    m1=xm1
    m2=min(ym1,xm2)
  else:
    m1=ym1
    m2=min(xm1,ym2)
  return (m1,m2,max(xM,yM))

n=input()
assert n[-1]!=" "
n=int(n)
a=input()
assert a[-1]!=" "
a=list(map(int,a.split()))
aa=[]
for i in a:
  aa.append((i,1000000000,i))
seg=SegmentTree(n,aa,(1000000000,1000000000,0),f)
ans=0
for l in range(n-1):
  r=seg.max_right(l, lambda x: x[2]<=x[0]+x[1])
  ans+=r-l-1
print(ans)