#include <bits/stdc++.h>
using namespace std;
int n, k;
vector<int> adj[500005];
int sz[500005];
int heavy[500005];
int depth[500005];
int head[500005];
int p[500005];
int pos[500005];
void dfs(int u){
sz[u] = 1;
int maxChild = 0;
for(int v : adj[u]){
if(sz[v] != 0) continue;
depth[v] = depth[u] + 1;
dfs(v);
sz[u] += sz[v];
p[v] = u;
if(sz[v] > maxChild){
heavy[u] = v;
maxChild = sz[v];
}
}
}
int cnt = 0;
void decompose(int u, int h){
head[u] = h;
pos[u] = cnt; cnt++;
if(heavy[u] != 0) decompose(heavy[u], h);
for(int v : adj[u]){
if(sz[v] < sz[u] && v != heavy[u]){
decompose(v,v);
}
}
}
int preState[500005];
int prefix[500005];
void update(int l, int r){
prefix[l]++;
prefix[r+1]--;
}
struct UFDS{
int p[500005];
void init() { for(int i = 0;i <= n;i++) p[i] = i; }
int findSet(int u){
if(p[u] == u) return u;
else return p[u] = findSet(p[u]);
}
void unionSet(int u, int v){
u = findSet(u); v = findSet(v);
if(u == v) return;
if((u^v)&1) swap(u,v);
p[u] = v;
}
} uf;
int compressAdj[500005];
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> k;
for(int i = 0;i < n-1;i++){
int a, b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
int root = -1;
for(int i = 1;i <= n;i++){
if(adj[i].size() != 1){
root = i;
break;
}
}
if(root == -1){ ///n==2 or n==1
cout << k-1; return 0;
}
dfs(root);
decompose(root, root);
//for(int i = 1;i <= n;i++) cout << pos[i] << " " << head[i] << "\n";
for(int i = 1;i <= n;i++){
int state; cin >> state;
if(preState[state] != 0){
int a = i, b = preState[state];
if(depth[a] > depth[b]) swap(a,b);
for(;head[a] != head[b];b = p[head[b]]){
if(depth[head[a]] > depth[head[b]]) swap(a,b);
update(pos[head[b]], pos[b]);
}
if(depth[a] > depth[b]) swap(a,b);
update(pos[a]+1,pos[b]);
}
preState[state] = i;
}
for(int i = 1;i <= n;i++) prefix[i] += prefix[i-1];
uf.init();
for(int i = 1;i <= n;i++){
if(i == root) continue;
if(prefix[pos[i]] == 0) continue;
uf.unionSet(i, p[i]);
}
for(int i = 1;i <= n;i++){
if(i == root) continue;
if(prefix[pos[i]] != 0) continue;
compressAdj[uf.findSet(i)]++;
compressAdj[uf.findSet(p[i])]++;
}
int leaves = 0;
for(int i = 1;i <= n;i++){
if(compressAdj[i] == 1) leaves++;
}
cout << (leaves+1)/2;
}
