#include <fstream>
#include <vector>
#include <cmath>
#define DIM 210000
using namespace std;
ifstream cin("lca.in");
ofstream cout("lca.out");
struct much {
	vector<int>c;
};
vector<much> mu;
int n, m, t[DIM], euler[DIM], lvl[DIM], first[DIM], rmq[DIM << 1][20], d[DIM];
void DFS(int poz, int nivel) {
	euler[0]++;
	euler[euler[0]] = poz;
	if (first[poz] == 0) {
		first[poz] = euler[0];
	}
	lvl[euler[0]] = nivel;
	for (int i = 0; i < mu[poz].c.size(); i++) {
		DFS(mu[poz].c[i], nivel + 1);
		euler[0]++;
		euler[euler[0]] = poz;
		lvl[euler[0]] = nivel;
	}
}
int main() {
	cin >> n >> m;
	for (int i = 0; i <= n; i++) {
		mu.emplace_back(much());
	}
	for (int i = 2; i <= n; i++) {
		cin >> t[i];
		mu[t[i]].c.emplace_back(i);
	}
	DFS(1, 0);
	int cnt = euler[0];
	for (int i = 1; i <= cnt; i++) {
		rmq[i][0] = i;
	}
	for (int j = 1, lg = 2; lg <= cnt; lg *= 2, j++) {
		for (int i = 1; i + lg <= cnt; i++) {
			int st = lvl[rmq[i][j - 1]];
			int dr = lvl[rmq[i + lg / 2][j - 1]];
			if (st < dr) {
				rmq[i][j] = rmq[i][j - 1];
			}
			else {
				rmq[i][j] = rmq[i + lg / 2][j - 1];
			}
		}
	}
	d[1] = 0;
	for (int i = 2; i <= cnt; i++) {
		d[i] = d[i / 2] + 1;
	}
}