#import sys #sys.setrecursionlimit(1000) import queue class sorted_list: def __init__(self): self.list = [] def _idx(self,val): if len(self.list) == 0: return 0 else: left = 0 right = len(self.list) -1 mid = int((left + right)/2) if val < self.list[left]: return 0 elif val > self.list[right]: return len(self.list) else: while right -left > 1: mid = int((left + right)/2) if val < self.list[mid]: right = mid else: left = mid return mid if val < self.list[mid] else mid +1 def insert(self,val): idx = self._idx(val) if idx < len(self.list): self.list.insert(self._idx(val), val) else: self.list.append(val) def remove(self, val): self.list.remove(val) def order_of_key(self, val): return self._idx(val) class Node: def __init__(self): #self.parent_Node = None self.child_Node = [] self.visited_cnt = 0 self.dns = 0 self.child_Node_visited_idx = -1 class tree: def __init__(self, Nodes): self.Nodes = Nodes self.sorted_list=sorted_list() def push_edge(self,low, upper): self.Nodes[upper].child_Node.append(low) def dns(self, val): stack = [] stack.append(val) #self.sorted_list.insert(val) while len(stack) > 0: v = stack.pop() self.Nodes[v].visited_cnt += 1 if len(self.Nodes[v].child_Node) == 0: self.Nodes[v].dns = self.sorted_list.order_of_key(v) elif self.Nodes[v].visited_cnt == len(self.Nodes[v].child_Node) + 1: self.sorted_list.remove(v) self.Nodes[v].dns = self.sorted_list.order_of_key(v) self.Nodes[v].dns += sum([self.Nodes[node].dns for node in self.Nodes[v].child_Node]) else: stack.append(v) stack.append(self.Nodes[v].child_Node[self.Nodes[v].child_Node_visited_idx +1]) if self.Nodes[v].child_Node_visited_idx == -1: self.sorted_list.insert(v) self.Nodes[v].child_Node_visited_idx += 1 return self.Nodes[val].dns N = int(input()) A = map(int, input().split()) t = tree([Node() for i in range(N)]) for idx, a in enumerate(A): t.push_edge(idx + 1, a) A = None N = None print(t.dns(0))