/**
_ _ __ _ _ _ _ _ _
|a ||t ||o d | |o |
| __ _| | _ | __| _ |
| __ |/_ | __ /__\ / _\|
**/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N_MAX = 200000;
int N, K;
vector <int> adj[N_MAX + 2];
int C[N_MAX + 2];
bool erased[N_MAX + 2];
vector <int> nodes;
int parent[N_MAX + 2];
int sub[N_MAX + 2];
bool in_comp[N_MAX + 2];
vector <int> with_color[N_MAX + 2];
void dfs (int u, bool first) {
if (first == true) {
nodes.push_back(u);
in_comp[u] = true;
}
sub[u] = 1;
for (int v : adj[u]) {
if (v != parent[u] && erased[v] == false) {
parent[v] = u;
dfs(v, first);
sub[u] += sub[v];
}
}
}
int answer = INT_MAX;
bool seen[N_MAX + 2];
bool cleared[N_MAX + 2];
void solve (int root) {
parent[root] = 0; dfs(root, true);
int centroid = 0;
for (int u : nodes) {
if (sub[root] - sub[u] > (int) nodes.size() / 2) {
continue;
}
bool ok = true;
for (int v : adj[u]) {
if (v != parent[u] && erased[v] == false && sub[v] > (int) nodes.size() / 2) {
ok = false;
break;
}
}
if (ok == true) {
centroid = u;
break;
}
}
root = centroid;
parent[root] = 0; dfs(root, false);
queue <int> q;
q.push(C[root]);
cleared[C[root]] = true;
int merges = 0;
while (q.empty() == false) {
int c = q.front(); q.pop();
for (int u : with_color[c]) {
if (in_comp[u] == false) {
merges = INT_MAX;
break;
}
while (u != 0 && seen[u] == false) {
if (cleared[C[u]] == false) {
cleared[C[u]] = true;
q.push(C[u]);
merges++;
}
seen[u] = true;
u = parent[u];
}
}
}
answer = min(answer, merges);
for (int u : nodes) {
in_comp[u] = false;
seen[u] = false;
cleared[C[u]] = false;
}
nodes.clear();
erased[root] = true;
for (int u : adj[root]) {
if (erased[u] == false) {
solve(u);
}
}
}
int main () {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> N >> K;
for (int i = 1; i <= N - 1; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int u = 1; u <= N; u++) {
cin >> C[u];
with_color[C[u]].push_back(u);
}
solve(1);
cout << answer << "\n";
return 0;
}
