local mfl, mce, mmi = math.floor, math.ceil, math.min
local SegTree = {}
SegTree.updateAll = function(self)
  for i = self.stagenum - 1, 1, -1 do
    for j = 1, self.cnt[i] do
      self.stage[i][j] = self.stage[i + 1][j * 2 - 1] + self.stage[i + 1][j * 2]
    end
  end
end
SegTree.create = function(self, n)
  local stagenum, mul = 1, 1
  self.cnt, self.stage, self.size = {1}, {{}}, {}
  while mul < n do
    mul, stagenum = mul * 2, stagenum + 1
    self.cnt[stagenum], self.stage[stagenum] = mul, {}
  end
  for i = 1, stagenum do self.size[i] = self.cnt[stagenum + 1 - i] end
  self.stagenum = stagenum
  for i = 1, mul do self.stage[stagenum][i] = 0 end
  self:updateAll()
end
SegTree.getRange = function(self, right)
  local start_stage = 1
  while right < self.size[start_stage] do
    start_stage = start_stage + 1
  end
  local ret = 0
  local t1, t2, t3 = {start_stage}, {1}, {right}
  while 0 < #t1 do
    local stage, l, r = t1[#t1], t2[#t1], t3[#t1]
    table.remove(t1) table.remove(t2) table.remove(t3)
    local sz = self.size[stage]
    if (l - 1) % sz ~= 0 then
      local newr = mmi(r, mce((l - 1) / sz) * sz)
      table.insert(t1, stage + 1) table.insert(t2, l) table.insert(t3, newr)
      l = newr + 1
    end
    if sz <= r + 1 - l then
      ret = ret + self.stage[stage][mce(l / sz)]
      l = l + sz
    end
    if l <= r then
      table.insert(t1, stage + 1) table.insert(t2, l) table.insert(t3, r)
    end
  end
  return ret
end
SegTree.setValue = function(self, idx, value, silent)
  self.stage[self.stagenum][idx] = value
  if not silent then
    for i = self.stagenum - 1, 1, -1 do
      local dst = mce(idx / 2)
      local rem = dst * 4 - 1 - idx
      self.stage[i][dst] = self.stage[i + 1][idx] + self.stage[i + 1][rem]
      idx = dst
    end
  end
end
SegTree.new = function(n)
  local obj = {}
  setmetatable(obj, {__index = SegTree})
  obj:create(n)
  return obj
end

local n = io.read("*n")
local edge = {}
local asked = {}
local calced = {}
for i = 1, n do
  edge[i] = {}
  asked[i] = false
  calced[i] = false
end
calced[1] = true
for i = 2, n do
  local a = 1 + io.read("*n")
  table.insert(edge[i], a)
  table.insert(edge[a], i)
end
local st = SegTree.new(n)

local tasks = {1}
local ret = 0
while 0 < #tasks do
  local src = tasks[#tasks]
  table.remove(tasks)
  asked[src] = true
  if not calced[src] then
    calced[src] = true
    ret = ret + st:getRange(src - 1)
  end
  local haschild = false
  while 0 < #edge[src] do
    local dst = edge[src][#edge[src]]
    if not asked[dst] then
      st:setValue(src, 1)
      haschild = true
      table.insert(tasks, src)
      table.insert(tasks, dst)
      table.remove(edge[src])
      break
    else
      table.remove(edge[src])
    end
  end
  if not haschild then
    st:setValue(src, 0)
  end
end
print(ret)