#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<deque>
#include<vector>
#include<string>
#include<math.h>
using namespace std;

#define INF 1000000000
#define lint long long
#define pb push_back
#define mp make_pair
#define MOD 1000000007

vector <int> g[100005];
int m;

int dfs(int v,int k)
{
    int i;
    int sum=1,cnt=0;
    multiset <int> s;
    for(i=0;i<g[v].size();++i)
    {
        int to=g[v][i];
        int cur=dfs(to,k);
        s.insert(cur);
        sum+=cur;
        ++cnt;
        while(cnt>k)
        {
            sum-=*s.begin();
            s.erase(s.begin());
            --cnt;
        }
    }
    return sum;
}

int check(int f)
{
    if(dfs(1,f)>=m)return 1;
    return 0;
}
int main()
{
    int n,i,j,x;
    scanf("%d %d",&n,&m);
    for(i=2;i<=n;++i)
    {
        scanf("%d",&x);
        g[x].pb(i);
    }
    if(check(0))
    {
        cout<<0;
        return 0;
    }
    int l=0,r=n+1;
    while(r-l>3)
    {
        int mid=(r+l)/2;
        if(check(mid))
        {
            r=mid;
        }
        else l=mid;
    }
    for(i=l;i<=r;++i)
    {
        if(check(i))
        {
            cout<<i;
            return 0;
        }
    }
    return 0;
}