from types import GeneratorType

def bootstrap(f, stack=[]):
    def wrappedfunc(*args, **kwargs):
        if stack:
            return f(*args, **kwargs)
        to = f(*args, **kwargs)
        while True:
            if type(to) is GeneratorType:
                stack.append(to)
                to = next(to)
            else:
                stack.pop()
                if not stack:
                    break
                to = stack[-1].send(to)
        return to
    return wrappedfunc

N = int(input())
P = list(map(int, input().split()))

MOD = 998244353

G = [[] for _ in range(N)]
for i, p in enumerate(P):
    G[p-1].append(i+1)

@bootstrap
def dfs(n):
    dp = [1, 0]
    for v in G[n]:
        ndp = yield dfs(v)
        SUM = size[n]+size[v]
        merge = [0]*(SUM+1)
        for i in range(size[n]+1):
            for j in range(size[v]+1):
                merge[i+j] += dp[i]*ndp[j]%MOD
                merge[i+j] %= MOD
        dp = merge
        size[n] += size[v]
    ndp = [0]*(size[n]+1)
    for i in range(size[n]+1):
        if dp[i] != 0:
            ndp[i] += dp[i]
            ndp[i] %= MOD
            ndp[i+1] += dp[i]
            ndp[i+1] %= MOD
    SUM = 0
    for i in reversed(range(size[n]+1)):
        ndp[i] += SUM
        ndp[i] %= MOD
        SUM += dp[i]
        SUM %= MOD
    yield ndp

size = [1]*N

print(sum(dfs(0))%MOD)