#include "september.h"
#include <bits/stdc++.h>
using namespace std;
void dfs(int u, int v, vector<vector<int>> &adj, unordered_set<int> &disconnected, unordered_set<int> &cleared){
if(!cleared.count(u)){
disconnected.insert(u);
for(int i = 0; i < adj[u].size(); i ++){
dfs(adj[u][i], u, adj, disconnected, cleared);
}
}
}
int solve(int N, int M, vector<int> F, vector<vector<int>> S) {
vector<vector<int>> adj(N, vector<int>());
for(int i = 1; i < F.size(); i ++){
adj[F[i]].push_back(i);
}
//vector<set<int>> disconnected(M, set<int>());
//vector<set<int>> cleared(M, set<int>());
unordered_set<int> disconnected[M];
unordered_set<int> cleared[M];
int days = 0;
for(int i = 0; i < S[0].size(); i ++){
for(int j = 0; j < S.size(); j ++){
dfs(S[j][i], 0, adj, disconnected[j], cleared[j]);
disconnected[j].erase(S[j][i]);
cleared[j].insert(S[j][i]);
}
int newday = 1;
for(int j = 0; j < S.size(); j ++){
if(!disconnected[j].empty()){
newday = 0;
}
if(newday){
if(j != 0){
if(cleared[j] != cleared[j-1]){
newday = 0;
}
}
}
}
days += newday;
}
return days;
}
/*
g++ -std=gnu++17 -O2 -o september stub.cpp september.cpp
1
5 2
0 0 2 2
3 4 1 2
4 3 2 1
*/
