#include "september.h"
#include <bits/stdc++.h>
using namespace std;
const int NM = 1e5;
struct segtree{
int data[4*NM+5];
void build(int id, int l, int r){
data[id] = -1;
if (l == r) return;
int mid = (l+r)/2;
build(2*id, l, mid);
build(2*id+1, mid+1, r);
}
void update(int id, int l, int r, int i, int val){
if (i < l || i > r) return;
if (l == r){
data[id] = max(data[id], val);
return;
}
int mid = (l+r)/2;
update(2*id, l, mid, i, val);
update(2*id+1, mid+1, r, i, val);
data[id] = max(data[2*id], data[2*id+1]);
}
int get(int id, int l, int r, int u, int v){
if (u > v || v < l || u > r) return -1;
if (l >= u && r <= v) return data[id];
int mid = (l+r)/2;
return max(get(2*id, l, mid, u, v), get(2*id+1, mid+1, r, u, v));
}
} ST1, ST2;
int N, M;
vector <int> son[NM+5];
int timer, tin[NM+5], tout[NM+5];
int sum[NM+5], res[NM+5];
void dfs(int u){
tin[u] = ++timer;
for (int v : son[u]) dfs(v);
tout[u] = timer;
}
int solve(int _N, int _M, vector <int> F, vector <vector <int> > S){
N = _N, M = _M;
for (int i = 0; i < N; i++) son[i].clear();
for (int i = 1; i < N; i++){
int p = F[i];
son[p].push_back(i);
}
timer = 0;
dfs(0);
for (int i = 0; i < M; i++){
for (int j = 1; j <= 4*N; j++){
ST1.data[j] = -1;
ST2.data[j] = -1;
}
for (int j = 0; j < N; j++) sum[j] = 0;
for (int j = N-2; j >= 0; j--){
int u = S[i][j];
int k = ST1.get(1, 1, N, tin[u], tout[u]);
if (k > j) sum[j]++, sum[k]--;
if (i > 0){
k = ST2.get(1, 1, N, 1, res[u]);
if (k > j) sum[j]++, sum[k]--;
}
ST1.update(1, 1, N, tin[u], j);
ST2.update(1, 1, N, res[u], j);
}
res[S[i][0]] = 1;
for (int j = 0; j < N-2; j++){
if (j > 0) sum[j] += sum[j-1];
if (sum[j] > 0) res[S[i][j+1]] = res[S[i][j]];
else res[S[i][j+1]] = res[S[i][j]]+1;
}
}
int mx = 0;
for (int i = 1; i < N; i++) mx = max(mx, res[i]);
return mx;
}
