#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001LL

int sz[5005];
mint dp[5005][5005];;

void dfs(int cv,vector<vector<int>> &E){
	sz[cv] = 1;
	rep(i,E[cv].size()){
		int to = E[cv][i];
		dfs(to,E);
		sz[cv] += sz[to];
	}
	vector<mint> tdp(2);
	tdp[1]= 1;
	rep(i,E[cv].size()){
		int to = E[cv][i];
		vector<mint> ndp(tdp.size() + sz[to]);
		rep(j,tdp.size()){
			rep(k,sz[to]+1){
				ndp[j+k] += tdp[j] * dp[to][k];
			}
		}
		swap(tdp,ndp);
	}
	mint sum = 0;
	for(int i=tdp.size()-1;i>=0;i--){
		sum += tdp[i];
		dp[cv][i] = sum;
	}
}

int main(){
	
	int n;
	cin>>n;
	vector<vector<int>> E(n);
	rep(i,n-1){
		int p;
		cin>>p;
		E[p-1].push_back(i+1);
	}
	dfs(0,E);
	
	mint ans = 0;
	rep(i,5005)ans += dp[0][i];
	
	cout<<ans.val()<<endl;
	
	return 0;
}