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

const int64_t MOD = 1e9+7;
void add(int64_t& a, int64_t b){
    a = (a+b) % MOD;
}
void mul(int64_t& a, int64_t b){
    a = a*b % MOD;
}

vector<int64_t> fact, seq_inv, fact_inv;

void create_fact_mod(int num){
    fact[0] = 1;
    fact[1] = 1;
    for(int i=2; i<=num; i++){
        fact[i] = fact[i-1] * i % MOD;
    }
}

void create_seq_inv_mod(int num){
    seq_inv[0] = 1;
    seq_inv[1] = 1;
    for(int i=2; i<=num; i++){
        seq_inv[i] = (MOD - MOD/i) * seq_inv[MOD%i] % MOD;
    }
}

void create_fact_inv_mod(int num){
    fact_inv[0] = 1;
    fact_inv[1] = 1;
    for(int i=2; i<=num; i++){
        fact_inv[i] = fact_inv[i-1] * seq_inv[i] % MOD;
    }
}

void create_mod_tables(int num){
    fact.resize(num+1);
    seq_inv.resize(num+1);
    fact_inv.resize(num+1);
    create_fact_mod(num);
    create_seq_inv_mod(num);
    create_fact_inv_mod(num);
}

int64_t comb_mod(int n, int k){
    return fact[n] * fact_inv[n-k] % MOD * fact_inv[k] % MOD;
}

int64_t perm_mod(int n, int k){
    return fact[n] * fact_inv[n-k] % MOD;
}

int64_t power_mod(int64_t num, int64_t power){
    int64_t prod = 1;
    num %= MOD;
    while(power > 0){
        if(power&1) prod = prod * num % MOD;
        num = num * num % MOD;
        power >>= 1;
    }
    return prod;
}

int64_t extgcd(int64_t a, int64_t b, int64_t& x, int64_t& y){
    int64_t d = a;
    if(b != 0){
        d = extgcd(b, a%b, y, x);
        y -= (a/b) * x;
    }else{
        x = 1; y = 0;
    }
    return d;
}

int64_t inv_mod(int64_t a){
    int64_t x, y;
    extgcd(a, MOD, x, y);
    return (MOD + x%MOD) % MOD;
}

int nth_bit(int64_t num, int n){
    return (num >> n) & 1;
}

vector<int> edges[2000];

int64_t dp[2001][2001][4], sub[2001][4];
int sz[2001];

void dfs(int i1){
    sz[i1] = 1;
    dp[i1][0][0] = 1;
    for(int i2 : edges[i1]){
        dfs(i2);
        memset(sub, 0, sizeof(sub));
        for(int j1=0; j1<sz[i1]; j1++){
            for(int j2=0; j2<sz[i2]; j2++){
                for(int k1=0; k1<4; k1++){
                    for(int k2=0; k2<4; k2++){
                        int64_t res = dp[i1][j1][k1] * dp[i2][j2][k2] % MOD;
                        add(sub[j1+j2][k1], res);
                        if(nth_bit(k1, 0) == 0 && nth_bit(k2, 1) == 0){
                            add(sub[j1+j2+1][k1+1], res);
                        }
                        if(nth_bit(k1, 1) == 0 && nth_bit(k2, 0) == 0){
                            add(sub[j1+j2+1][k1+2], res);
                        }
                    }
                }
            }
        }
        sz[i1] += sz[i2];
        for(int j=0; j<sz[i1]; j++) for(int k=0; k<4; k++) dp[i1][j][k] = sub[j][k];
    }
}

int main(){
    int N;
    cin >> N;
    for(int i=1; i<N; i++){
        int p;
        cin >> p;
        edges[p-1].push_back(i);
    }

    dfs(0);

    create_mod_tables(2000);
    int64_t ans = 0;
    for(int j=0; j<N; j++){
        int64_t res = 0;
        for(int k=0; k<4; k++) add(res, dp[0][j][k]);
        mul(res, fact[N-j]);
        add(ans, j%2 ? (MOD - res) : res);
    }
    cout << ans << endl;
    return 0;
}
