#include <stdio.h>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
int N,M,K;
vector<int> edge[100002];
int dfs(int x){
int i,v,sum;
priority_queue<int> q;
for(i=0; i<edge[x].size(); i++){
v = edge[x][i];
q.push(dfs(v));
}
i = K;
sum = 1;
while(i > 0 && !q.empty()){
sum += q.top();
q.pop();
i--;
}
return sum;
}
bool checking(){
if(dfs(1) >= M) return true;
return false;
}
int main(){
int i,ans;
int l,mid,r;
//freopen("input.txt","r",stdin);
scanf("%d %d",&N,&M);
for(i=1; i<N; i++){
scanf("%d",&ans);
edge[ans].push_back(i+1);
}
l = 0; r = N-1;
while(l <= r){
mid = (l+r)/2;
K = mid;
if(checking()){
ans = mid;
r = mid-1;
}else l = mid+1;
}
printf("%d",ans);
return 0;
}
