/*
 /+==================================================+\
//+--------------------------------------------------+\\
|.|\\...>>>>>>> Hollwo_Pelw(ass) 's code <<<<<<<...//|.|
\\+--------------------------------------------------+//
 \+==================================================+/
*/
#include <bits/stdc++.h>
using namespace std;
// type
typedef long long ll;
typedef long double ld;
// loop
//#define For(i, l, r)        for (int i = l; i < r; i++)
//#define ForE(i, l, r)       for (int i = l; i <= r; i++)
//#define Ford(i, r, l)       for (int i = r; i > l; i--)
//#define FordE(i, r, l)      for (int i = r; i >= l; i--)
//#define Fora(i, a)          for (auto i : a)
// I/O
#define open(file, in, out) if (fopen(file in, "r")) {        \
                                freopen(file in, "r", stdin);  \
                                freopen(file out, "w", stdout); \
                            }
#define FAST_IO             std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define setpre(n)           fixed << setprecision(n)
// pair
#define F                   first
#define S                   second
#define pii                 pair<int, int>
#define pll                 pair<ll, ll>
#define pdd                 pair<ld, ld>
// vector & !!?(string)
#define eb                  emplace_back
#define pb                  push_back
#define all(a)              a.begin(), a.end()
#define rall(a)             a.rbegin(), a.rend()
#define sz(a)               a.size()
// geometry calculate
#define pi                  acos(-1.0)
#define g_sin(a)            sin(a*pi/180)
#define g_cos(a)            cos(a*pi/180)
#define g_tan(a)            tan(a*pi/180)
// set val
#define ms0(a)              memset(a,        0, sizeof(a));
#define ms1(a)              memset(a,        1, sizeof(a));
#define msn1(a)             memset(a,       -1, sizeof(a));
#define msinf(a)            memset(a, 0x3f3f3f, sizeof(a));
// constant
const int mod1 = 998244353, mod = 1e9+7;
const int MAXN = 2e5 + 10, MAXM = 1e5 + 5, VV = 5e8 + 4;
// code
#define int long long

int n, p, sz[MAXN], w[MAXN];
int ans;
vector<int> adj[MAXN];
deque<pii> dp[MAXN];
void merge(pii &a, pii &b){
    a.F = (a.F*b.S + a.S*b.F) % mod;
    a.S = a.S*b.S % mod;
}
void rev(pii &a){
    a.S = (mod - a.F + 1) % mod;
}
void dfs(int u){
	int f = w[u] = u, s = 0;
	for(int &nx: adj[u]){
		dfs(nx);
		if(sz[f] < sz[nx]){
			s = sz[f];
			swap(f,nx);
		}else if(s < sz[nx]){
		    s = sz[nx];
        }
		for(int i = 0; i < sz[nx]; i++) 
		    merge(dp[w[f]][i], dp[w[nx]][i]);
	}
	for(int i = 0; i < s; i++) 
	    rev(dp[w[f]][i]);
	dp[w[f]].push_front({VV, VV});
	
	w[u] = w[f];
	sz[u] = sz[f] + 1;
	
}

void Solve(){
  	//cout << (int) (5e8+4) * (int) (5e8+4) % mod;
  	cin >> n;
	for(int i = 1; i <= n; i++){
		cin >> p;
		adj[p].push_back(i);
	}
	dfs(0);
	for(auto t: dp[w[0]]) ans += t.F;
	ans %= mod;
	//cout << ans << endl;
	int k = n+1, p = 2;
	while(k){
	    if (k & 1) (ans *= p) %= mod;
	    (p *= p) %= mod; k /= 2;
	}
	cout << ans << endl;
}


signed main(){
    open("", ".inp", ".out");
    FAST_IO;
    int TC = 1;
    //cin >> TC;
    while(TC--) Solve();
    return 0;
}
/*
./-=====>>><<<-------- DEBUG -------->>><<<=====-\.
/.................................................\

+====================== INP ======================+


+====================== OUT ======================+


\................................................./
.\-=====>>><<<--------= END =-------->>><<<=====-/.
*/


Measured memory_bytes: 249952