#include <cstdio>
#include <vector>
#include <queue>
#include <iostream>
using namespace std;
vector <long long int> b, d;
long long int N;
queue <long long int> q;
vector<long long int> G[100000];
void addEdge(long long int a, long long int b)
{
  G[a].push_back(b);
  G[b].push_back(a);
}
int main()
{

        cin >> N;
        long long int p;
        for (int i = 0; i < N; i++)
	{
                cin >> p;
                addEdge(i + 1, p);
                b.push_back(0);
                d.push_back(0);
        }

                long long int t = 0;
                q.push(0);
                while (!q.empty())
                {

                        long long int u = q.front();
                        q.pop();

                        for(long long int i = 0; i < G[u].size(); ++i)
                        {
                                long long int v =G[u][i];
                                        if (b[v] == 0)
                                        {
                                                b[v] = 1;
                                                b[u] = 1;
                                                d[v] = d[u] + 1;
                                                q.push(v);
                                                if ( v == N) t = 1;
                                        }

                        }

                }




                 long long int m = 0, m1 = 0;
                if (t == 0) N = N - 1;
               for (long long int u = 0; u <= N; u++)
                        if (d[u] > m)
                        {
                                 m = d[u];
                                 m1 = u;

                        }


                 cout << m1;
	return 0;
}