#include<bits/stdc++.h>
using namespace std;

int n;
int tree[100005];
int sons[100005];
int sum = 0;

int main(){
	cin>>n;
	for(int i = 2;i <= n;i++){
		cin>>tree[i];
		sons[tree[i]]++;
	}
	int i = n;
	while(i != 1){
		sum += sons[tree[i]];
		i = tree[i];
	}
	cout<<sum;
	return 0;
}

我是有什么没考虑到的地方吗？