#include <bits/stdc++.h>
#include "september.h"
using namespace std;
//#define int long long
#define speedIO ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//#define mod 1000000007
#define f first
#define s second
#define pii pair<int,int>
#define pb push_back
vector<vector<int>> graph;
vector<int> super,mpos;
void dfs(int u, int p){
super[u]=mpos[u];
for(int v:graph[u]){
if(v==p) continue;
dfs(v,u);
super[u]=max(super[u],super[v]);
}
}
int solve(int n, int m, vector<int> f, vector<vector<int>> s){
graph.clear();
graph.resize(n+1);
super.clear();
super.resize(n,-1);
mpos.clear();
mpos.resize(n+1);
for(int i=1;i<n;i++){
graph[i].pb(f[i]);
graph[f[i]].pb(i);
}
for(int i=0;i<m;i++){
for(int j=0;j<n-1;j++){
mpos[s[i][j]]=max(mpos[s[i][j]],j);
}
}
dfs(0,-1);
int day=0;
int idx=0;
int right=0;
while(idx<n-1){
day++;
right=super[s[0][idx]];
while(idx<=right){
for(int j=0;j<m;j++){
right=max(right,super[s[j][idx]]);
}
idx++;
}
}
return day;
}
