#include <bits/stdc++.h>
using namespace std;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int n; long long k;
    cin >> n >> k;
    
    vector<int> blackSeeds;
    blackSeeds.resize(0);
    vector<int> isBlack(n+1,0);
    
    // 读取初始黑点
    for(int i = 0; i < k; i++){
        int x;
        cin >> x;
        isBlack[x] = 1;
        blackSeeds.push_back(x);
    }
    
    // 构建树的邻接表
    vector<vector<int>> adj(n+1);
    for(int i = 0; i < n-1; i++){
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    
    // 多源 BFS 计算距离
    vector<int> dist(n+1, -1);
    deque<int> dq;
    for(int b : blackSeeds){
        dist[b] = 0;
        dq.push_back(b);
    }
    
    while(!dq.empty()){
        int u = dq.front();
        dq.pop_front();
        for(int nei : adj[u]){
            if(dist[nei] == -1){
                dist[nei] = dist[u] + 1;
                dq.push_back(nei);
            }
        }
    }
    
    // 统计最大距离并构造频率数组
    int maxd = 0;
    for(int i = 1; i <= n; i++){
        if(dist[i] > maxd) maxd = dist[i];
    }
    
    vector<int> freq(maxd+2, 0);
    for(int i = 1; i <= n; i++){
        if(dist[i] >= 0 && dist[i] <= maxd) 
            freq[dist[i]]++;
    }
    
    // 找到第 k 个点的距离 d_k
    long long cum = 0;
    int d_k = 0;
    for(int d = 0; d <= maxd; d++){
        cum += freq[d];
        if(cum >= k){
            d_k = d;
            break;
        }
    }
    
    // 答案是距离恰好为 d_k+1 的点的数量
    int target = d_k + 1;
    long long ans = 0;
    if(target <= maxd) 
        ans = freq[target];
    else 
        ans = 0;
    
    cout << ans << "\n";
    
    return 0;
}