#include <bits/stdc++.h>

#include <unistd.h>
 
using namespace std;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
 
 
typedef long long ll;
//#define int ll
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx_ori[4] = { -1,0, 1,0 }, dy_ori[4] = { 0,1,0,-1 };
int dx[4] = {0, 0, 0, 0}, dy[4] = {0, 0, 0, 0};
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
const ll MOD = 1000000007;
//const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'

using arr = array<ll, 3>;
vii G;
int depth[222222];
ll power2[222222];


deque<arr> dfs(int now, int par, int d) {
  depth[d]++;
  deque<arr> p1, p2;
  int ma = 0;
  for (int ch: G[now]) {
    if (ch == par) continue;
    p2 = dfs(ch, now, d + 1);

    // p1とp2をマージする、マージした結果がp1となる
    if (p1.size() == 0) {
      swap(p1, p2);
      continue;
    }
    if (p1.size() < p2.size()) swap(p1, p2);

    chmax(ma, (int)p2.size());
    rep (i, p2.size()) {
      rrep (j1, 3) {
        ll memo = p1[i][j1];
        p1[i][j1] = 0;
        rep (j2, 3) {
          int nj = (j1 + j2);
          if (nj > 2) nj = 2;
          p1[i][nj] += p2[i][j2] * memo % MOD;
          if (p1[i][nj] >= MOD) p1[i][nj] -= MOD;
        }
      }
    }
  }

  if (p1.size() > 0) {
    rep (i, ma) {
      p1[i][0] += p1[i][2];
      if (p1[i][0] >= MOD) p1[i][0] -= MOD;
      p1[i][2] = 0;
    }
  }
  
  arr temp;
  temp[0] = temp[1] = 1;
  temp[2] = 0;
  p1.push_front(temp);
  return p1;
}


signed main() {
  fio();
  int n;
  cin >> n;
  n++;
  G.resize(n);
  vi p(n, -1);
  rep1 (i, n - 1) {
    cin >> p[i];
    G[p[i]].push_back(i);
    G[i].push_back(p[i]);
  }

  auto res = dfs(0, -1, 0);

  power2[0] = 1;
  rep (i, n) {
    power2[i + 1] = power2[i] * 2 % MOD;
  }
  
  ll ans = 0;
  int d = 0;
  for (auto temp: res) {
    ans += temp[1] * power2[n - depth[d]] % MOD;
    d++;
  }
  ans %= MOD;
  cout << ans << endl;
}


Measured memory_bytes: 317440