#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;
const int N = 1e3 + 5;
const int oo = 1e18 + 7, mod = 1e9 + 7;
int n, d;
vector<int> Adj[N];
int dist[N][N];
void dfs(int u, int p, int root){
for(auto v : Adj[u]){
if(v == p) continue;
dist[root][v] = dist[root][u] + 1;
dfs(v, u, root);
}
}
void process(){
cin >> n >> d;
for(int i = 1; i < n; i++){
int x;
cin >> x;
Adj[x].pb(i);
Adj[i].pb(x);
}
for(int i = 0; i < n; i++){
dfs(i, i, i);
}
int mx = -1;
for(int i = 0; i < (1LL << n); i++){
vector<int> vc;
for(int j = 0; j < n; j++) if(i & (1LL << j)) vc.pb(j);
bool ck = 1;
for(auto it : vc){
for(auto it2 : vc){
if(it == it2) continue;
ck &= (dist[it][it2] >= d);
}
}
if(ck) mx = max(mx, (int)vc.size());
}
cout << mx;
}
signed main(){
ios_base::sync_with_stdio(0);
process();
}
