#include<bits/stdc++.h>
#define pb(x) push_back(x)
#define all(x) x.begin(), x.end()
#define ones(x) __builtin_popcount(x)
#define cout2(x, y) cout << x << " " << y << endl
#define cout3(x, y, z) cout << x << " " << y << " " << z << endl
#define N 200005

using namespace std;

int level[N], deg[N], P[N];
vector<int>L[N];

int DFS(int u, int pd, int l){

	level[u] = l;
	for(int i = 0, v; i < L[u].size(); i++){
		
		v = L[u][i];
		if(v != pd)DFS(v, u, l + 1);
	}
}

int main(){

	int n, u, v;
	scanf("%d", &n);
	
	
	for(int i = 0; i <= n; i++)L[i].clear(), deg[i] = 0;
	P[1] = -1;
	
	for(int i = 2; i <= n; i++){
		
		scanf("%d", &P[i]);
		deg[P[i]]++;
		
		L[i].pb(P[i]);
		L[P[i]].pb(i);
	}
	
	DFS(1, -1, 0);
	
	set<pair<int, int> >E;
	for(int i = 2; i <= n; i++)E.insert(make_pair(-level[i], i));

	pair<int, int> e, aux;
	int ans = 0;

	while(E.size() > 0){
	
		e = (*E.begin());
		E.erase(E.begin());
		
		u = e.second;
		v = P[u];
		//printf("%d %d %d %d\n", u, v, deg[u], deg[v]);
		aux = make_pair(-level[v], v);
		if(deg[u] >= 2 && deg[v] >= 3 && v != 1 && E.find(aux) != E.end())E.erase(aux), deg[P[v]]--, ans++;
	}
	
	printf("%d\n", ans);	
}