#include <bits/stdc++.h>
using namespace std;
 
vector<vector<int>> adj;
unordered_set<int> S;
long long moves = 0;
 
bool dfs(int node, int parent) {
    bool has = (S.count(node) > 0);
 
    for (int it : adj[node]) {
        if (it == parent) continue;
 
        if (dfs(it, node)) {
            moves += 2;
            has = true;
        }
    }
    return has;
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int n, t;
    cin >> n >> t;
 
    adj.resize(n + 1);
 
    for (int i = 0; i < t; i++) {
        int x;
        cin >> x;
        S.insert(x);
    }
 
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
 
    dfs(1, 0);
    cout << moves << "\n";
    return 0;
}
 

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