#include "september.h"
#include <algorithm>
#include <iostream>
#include <climits>
#include <bitset>
#include <vector>
#include <set>
int dfs(std::vector<int>& F, std::set<int>& leafs, int* depth, int n) {
if (depth[n] != INT_MAX) return depth[n];
if (F[n] == -1) return 0;
auto parent = leafs.find(F[n]);
if (parent != leafs.end())
leafs.erase(parent);
depth[n] = dfs(F, leafs, depth, F[n]) + 1;
return depth[n];
}
int solve(int N, int M, std::vector<int> F, std::vector<std::vector<int>> S) {
std::set<int> leafs;
int depth[N];
for (int x = 0; x < N; x++)
depth[x] = INT_MAX, leafs.insert(x);
for (int x = 1; x < N; x++)
dfs(F, leafs, depth, x);
std::bitset<100005> rem;
int days = 0;
bool bad = 0;
for (auto record: S) {
std::sort(record.begin(), record.end(), [&] (int a, int b) {
if (depth[a] == depth[b]) return a > b;
return depth[a] > depth[b];
});
bool g = 1;
for (int lf: record) {
auto leaf = leafs.find(lf);
if (leaf == leafs.end()) {
g = 0;
break;
}
if (F[lf] != -1)
leafs.insert(F[lf]);
N--;
leafs.erase(leaf);
}
if (!g) {
bad = 1;
break;
}
days++;
}
if (!bad) return days + N;
return days;
}
