#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#define ll long long
#define int long long
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(a) (a).begin(), (a).end()
#define fore(i, a) for (auto& i : a)
#define MP make_pair
using namespace std;
using ld = long double;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using Graph = vector<vector<ll>>;
using in = int;
using vin = vector<in>;
using vvin = vector<vector<int>>;
using PQS = priority_queue<int, vector<int>, greater<int>>;
using PQ = priority_queue<int>;
const ll MOD = 1e9 + 7;
const ll INF = 1LL << 60;
const string YYY = "YES";
const string yyy = "Yes";
const string NNN = "NO";
const string nnn = "No";
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
template <class T>
bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  } else {
    return false;
  }
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T& val) {
  std::fill((T*)array, (T*)(array + N), val);
}
template <class T>
bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  } else {
    return false;
  }
}
bool cmp(const pll& a, const pll& b) { return a.second > b.second; }
ll GD(ll num) {  //各桁の和
  ll digit = 0;
  while (num != 0) {
    digit += num % 10;
    num /= 10;
  }
  return digit;
}
bool if_integer(ld x) {  //整数判定
  return std::floor(x) == x;
}
bool if_prime(ll x) {
  bool a = true;
  for (ll i = 2; i * i <= x; i++) {
    if (x % i == 0) {
      a = false;
      break;
    }
  }
  if (x == 1) a = false;
  return a;
}
ll gcd(ll x, ll y) {
  if (x % y == 0) {
    return (y);
  } else {
    return (gcd(y, x % y));
  }
}
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }
int GetDigit(int num) {
  int digit = 0;
  while (num != 0) {
    num /= 10;
    digit++;
  }
  return digit;
}
vector<int> bfs(Graph G, int N, int s) {
  vin d(N, -1);
  d[s] = 0;
  queue<int> que;
  que.push(s);
  while (!que.empty()) {
    int v = que.front();
    que.pop();
    for (auto nv : G[v]) {
      if (d[nv] != -1) {
        continue;
      }
      d[nv] = d[v] + 1;
      que.push(nv);
    }
  }
  return d;
}
signed main() {
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  cout << std::fixed << std::setprecision(50);
  ////////////////////////////
  ///////////////////////////
  in N;
  cin >> N;
  Graph G(N);
  rep(i, N - 1) {
    in a;
    cin >> a;
    a--;
    G[i].push_back(a);
  }
  auto d = bfs(G, N, 0);
  cout << d[N - 1] << endl;
}

//
// rm -rf test/ && oj d
// g++ main.cpp
//  oj t --ignore-spaces-and-newline