#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
#define pb push_back
#define mp make_pair
int in[100100], out[100100], sz[100100], timer = 0;
vi G[100100];
template <class T> class BIT {
private:
    int size;
    vector<T> bit;
    vector<T> arr;

public:
    BIT(int size) : size(size), bit(size + 1), arr(size) {}

    void set(int ind, int val) { add(ind, val - arr[ind]); }

    void add(int ind, int val) {
        arr[ind] += val;
        ind++;
        for (; ind <= size; ind += ind & -ind) { bit[ind] += val; }
    }

    T pref_sum(int ind) {
        ind++;
        T total = 0;
        for (; ind > 0; ind -= ind & -ind) { total += bit[ind]; }
        return total;
    }
};

void dfs(int node, int prev){
    in[node] = timer++;
    sz[node] = 1;
    for(auto next : G[node]){
        if(next != prev){
            dfs(next, node);
            sz[node] += sz[next];
        }
    }
    out[node] = timer;
}
bool is_ancestor(int u, int v){
    return in[u] <= in[v] && out[u] >= out[v];
}
int solve(int N, int M, std::vector<int> F, std::vector<std::vector<int>>S){
    if(M > 1)   return 0;
    for(int i = 0; i <= N; i++)  G[i].clear();
    memset(in, 0, sizeof in);
    memset(out, 0, sizeof out);
    memset(sz, 0, sizeof sz);
    timer = 0;
    for(int i = 1; i < F.size(); i++){
        G[F[i]].pb(i);
        G[i].pb(F[i]);
    }
    dfs(0, -1);
    BIT<long long> bit(N+10);
    int ans = 0, not_out = -1;
    for(auto idx : S[0]){
        bit.add(in[idx], 1);
        if(not_out == -1)   not_out = idx;
        else{
            if(is_ancestor(idx, not_out)){
                not_out = idx;
            }
        }
        ll end_sum = bit.pref_sum(out[not_out]-1);
        ll start_sum;
        if(in[not_out] == 0)    start_sum = 0;
        else start_sum = bit.pref_sum(in[not_out]-1 );
        if(end_sum - start_sum == sz[not_out]){
            ans++;
            not_out = -1;
        }
    }
    return ans;
}