#include<stdio.h>
#include<stdlib.h>

typedef struct directedGraph{
  int *vertex;
  int *next;
  int *start;
  int v,e;
  int pointer;
} graph;

graph* newGraph(const int v,const int e){
  graph *g=(graph *)malloc(sizeof(graph));
  g->vertex=(int *)calloc(e,sizeof(int));
  g->next=(int *)calloc(e,sizeof(int));
  g->start=(int *)calloc(v,sizeof(int));
  for(int i=0;i<v;i++) g->start[i]=-1;
  g->v=v;
  g->e=e;
  g->pointer=0;
  return g;
}

void freeGraph(graph *g){
  free(g->vertex);
  free(g->next);
  free(g->start);
  free(g);
  return;
}

void addEdge(graph *g,const int from,const int to){
  const int p=g->pointer;
  g->vertex[p]=to;
  g->next[p]=g->start[from];
  g->start[from]=p;
  g->pointer++;
  return;
}

typedef long long int int64;

void add(int *bit,int index,int v){
  index++;
  const int n=bit[0];
  for(int i=index;i<=n;i+=i&-i) bit[i]+=v;
}

int sum(int *bit,int index){
  index++;
  int res=0;
  for(int i=index;i>0;i-=i&-i) res+=bit[i];
  return res;
}

int64 calc(int v,int *bit,graph *g,int *used){
  if(used[v]) return 0;
  used[v]=1;
  int64 res=sum(bit,v);
  add(bit,v,1);
  for(int p=g->start[v];p!=-1;p=g->next[p]){
    int u=g->vertex[p];
    res+=calc(u,bit,g,used);
  }
  add(bit,v,-1);
  return res;
}

void run(void){
  int n;
  scanf("%d",&n);
  graph *g=newGraph(n,2*n);
  int i;
  for(i=1;i<n;i++){
    int a;
    scanf("%d",&a);
    addEdge(g,a,i);
    addEdge(g,i,a);
  }
  int *bit=(int *)calloc(n+1,sizeof(int));
  bit[0]=n;
  int *used=(int *)calloc(n,sizeof(int));
  int64 ans=calc(0,bit,g,used);
  printf("%lld\n",ans);
}

int main(void){
  run();
  return 0;
}