#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define f0r(i, n) for (auto i = 0; i < (n); ++i)
#define fnr(i, n, k) for (auto i = (n); i < (k); ++i)
#define all(v) (v).begin(), (v).end()
#define pb push_back
#define F first
#define S second
#define ctn(x) cout << x << '\n'
#define forl(a, l) for (auto a : l)
#define ctl(l) for (auto &a : (l)) cout << a << ' '; cout << endl;
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define ub(v, x) (upper_bound(all(v), x) - begin(v))
#define pq priority_queue
template <class T>
using V = vector<T>;
using ll = long long;
using vi = V<int>;
using vl = V<ll>;
using pi = pair<int, int>;
using ti = tuple<int, int, int>;
using Adj = V<vi>;
using vvi = V<vi>;
#include "september.h"
int solve(int N, int M, vi F, V<vi> S) {
vi pos(N);
f0r(j, M) {
f0r(i, N-1) {
pos[S[j][i]] = max(pos[S[j][i]], i);
}
}
vi deg(N);
fnr(i, 1, N) deg[F[i]]++;
int day = 0, cnt = 0;
set<pi> st;
f0r(i, N) if (!deg[i]) st.insert({pos[i], i});
while (cnt < N-1) {
int mx = -1e9;
while (mx+1 != cnt) {
auto [i, u] = *st.begin();
st.erase(st.begin());
mx = max(mx, i);
int p = F[u];
if (--deg[p] == 0) st.insert({pos[p], p});
++cnt;
}
++day;
}
return day;
}
