#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define FOR(a , b) for(int i = a;i <= b;i++)
#define pb push_back
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int MXN = 2e5 + 5;
const int INF = 1e18;
int N , D;
vector < int > adj[MXN];
int get_dia()
{
queue < int > q;
vector < int > d(N + 1 , INF);
q.push(1);
d[1] = 0;
while(!q.empty())
{
int v = q.front();
q.pop();
for(int u : adj[v]){
if(d[u] == INF){
d[u] = d[v] + 1;
q.push(u);
}
}
}
int mx = -1 , node = -1;
for(int i = 1;i <= N;i++){
if(d[i] > mx)
{
node = i;
mx = d[i];
}
}
q = {};
d.assign(N + 1 , INF);
q.push(node);
d[node] = 0;
while(!q.empty())
{
int v = q.front();
q.pop();
for(int u : adj[v]){
if(d[u] == INF){
d[u] = d[v] + 1;
q.push(u);
}
}
}
mx = -1;
for(int i = 1;i <= N;i++) mx = max(mx , d[i]);
return mx;
}
void solve()
{
cin >> N >> D;
for(int i = 2;i <= N;i++)
{
int u;
cin >> u;
++u;
adj[i].push_back(u);
adj[u].push_back(i);
}
int d = get_dia();
cout << d / D + 1 << endl;
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);
int T = 1;
//cin >> T;
FOR(1 , T) solve();
}
