#ifdef MAIN 
bool __multi__ = 0;

namespace XK {

  void solve() {
  	int N; cin >> N;
  	V<int> P(N), fa(N, -1);
  	rep(i, N) {
  		cin >> P[i];
  		if(P[i] != 0) -- P[i];
  	}
  	rep(i, N) if(P[i] != 0) fa[P[i]] = i;
  	ll ans = 0;
  	rep(i, N) {
  		if(fa[i] == -1) continue;
  		if(fa[fa[i]] == -1) continue;
  		if(fa[fa[fa[i]]] == -1) ans ++;
  	}
  	cout << ans;
  }
};

#else
#include "cassert"
#include "cmath"
#include "cstdint"
#include "cstdio"
#include "cstdlib"
#include "cstring"
#include "algorithm"
#include "bitset"
#include "chrono"
#include "complex"
#include "deque"
#include "functional"
#include "iostream"
#include "limits"
#include "map"
#include "numeric"
#include "queue"
#include "random"
#include "set"
#include "sstream"
#include "string"
#include "unordered_map"
#include "unordered_set"
#include "utility"
#include "vector"
#include "array"
using namespace std;
#define int long long
using ll = long long;
using ull = unsigned long long;
const ll INF = 1ll << 60;
const ll LINF = 0x1fffffffffffffff;
const ll MINF = 0x7fffffffffff;
template <class A, class B> bool chmax(A& l, const B& r){ return r > l ? l = r, 1 : 0; }
template <class A, class B> bool chmin(A& l, const B& r){ return r < l ? l = r, 1 : 0; }
#define sz(x) ssize(x)
#define rep(i, a) for(ll i = 0; i < (a); i ++)
#define Rep(i, a, b) for(ll i = (a); i < (b); i ++)
#define rrep(i, a, b) for(ll i = (b); i --> (a); )
#define all(x) begin(x), end(x)
#define fst first
#define snd second
#define pb push_back
template<class T> using V = vector<T>;
template<class T, std::size_t N> using AR = array<T, N>;
#define MAIN
#include __FILE__
signed main() {ios::sync_with_stdio(0);cin.tie(0);fixed(cout).precision(12);int t = 1;if(__multi__) cin >> t;while(t --) XK::solve();}
#endif