///Enta etfsh5t nseet el rank

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")

#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update

using namespace std;
using namespace __gnu_pbds;

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,
        tree_order_statistics_node_update>;
#define pb push_back
#define F first
#define S second
#define f(i, a, b) for (int i = a; i < b; i++)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define sz(x) (int)(x).size()
//#define mp(x, y) make_pair(x, y)
#define popCnt(x) (__builtin_popcountll(x))
#define int ll

using ll = long long;
using ull = unsigned long long;
using uint = uint32_t;
using ii = pair<int, int>;

const int N = 1e5 + 20, LG = 18, MOD = (119 << 23) + 1;
const long double PI = acos(-1);

const long double EPS = 1e-9;

struct PT {
    int index, val;
    int x, y;

    bool operator<(const PT &p) { return x * p.y > p.x * y; }
};

set<int> adj[N];
bool inStack[N];
queue<int> q;

void dfs(int node) {
    inStack[node] = true;
    for (auto v: adj[node])
        dfs(v);
    while (inStack[q.front()])q.pop();
    inStack[node] = false;
}

void doWork() {
    int n, m;
    cin >> n >> m;
    f(i, 1, n) {
        int u, v;
        cin >> u >> v;
        adj[u].insert(v);
    }
    f(i, 0, m) {
        int d;
        cin >> d;
        q.push(d);
    }
    q.push(0);
    dfs(1);

    cout << m + 1 - q.size() << '\n';
}

int32_t main() {
#ifdef ONLINE_JUDGE
    ios_base::sync_with_stdio(0);
    cin.tie(0);
#endif // ONLINE_JUDGE
    int t = 1;
//    cin >> t;
    while (t--)
        doWork();
    return 0;
}