#include <bits/stdc++.h>
using namespace std;
const int N = 200'000 + 10,
MAX = 1'000'000;
int n, k;
vector<int> ad[N];
int c[N];
bool mk[N];
int sz[N], totalSize;
void initDFS(int u, int p = -1) {
sz[u] = 1;
for (const auto& v : ad[u]) {
if (mk[v] || v == p) continue;
initDFS(v, u);
sz[u] += sz[v];
}
totalSize = sz[u];
}
int centroid(int u, int p = -1) {
for (const auto& v : ad[u]) {
if (mk[v] || v == p) continue;
if (sz[v] > totalSize / 2) return centroid(v, u);
}
return u;
}
int par[N];
vector<int> nodes;
void collectDFS(int u, int p = -1) {
nodes.push_back(u);
for (const auto& v : ad[u]) {
if (mk[v] || v == p) continue;
par[v] = u;
collectDFS(v, u);
}
}
int id[N];
int root(int u) { return id[u] < 0 ? u : id[u] = root(id[u]); }
void join(int u, int v) {
u = root(u); v = root(v);
if (id[u] > id[v]) swap(u, v);
if (u == v) return;
id[u] += id[v];
id[v] = u;
}
vector<int> pos[N];
int cntC[N];
bool mkC[N];
int answer = MAX;
void dfs(int u, int p = -1) {
initDFS(u, p);
mk[u = centroid(u, p)] = true;
nodes = {u};
for (const auto& v : ad[u]) {
if (mk[v] || v == p) continue;
par[v] = u;
collectDFS(v, u);
}
for (const auto& x : nodes) cntC[c[x]] += 1;
int totalC = 0;
queue<int> q({c[u]});
mkC[c[u]] = true;
while (q.size()) {
auto color = q.front(); q.pop();
totalC += 1;
if (cntC[color] != (int)pos[color].size()) {
totalC = MAX;
break;
}
for (auto x : pos[color]) {
for (; root(x) != root(u); x = par[x]) {
if (!mkC[c[x]]) {
q.push(c[x]);
mkC[c[x]] = true;
}
join(x, u);
}
}
}
answer = min(answer, totalC - 1);
for (const auto& x : nodes) {
cntC[c[x]] = 0;
mkC[c[x]] = false;
id[x] = -1;
}
for (const auto& v : ad[u]) {
if (mk[v] || v == p) continue;
dfs(v, u);
}
}
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> k;
for (int i = 1; i < n; ++i) {
int u, v; cin >> u >> v;
ad[u].push_back(v);
ad[v].push_back(u);
}
for (int i = 1; i <= n; ++i) cin >> c[i];
for (int i = 1; i <= n; ++i) pos[c[i]].push_back(i);
memset(id, -1, sizeof id);
dfs(1);
cout << answer << "\n";
}
