#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 2e5 + 2;
const int inf = 1e9;
vector<int> g[N];
int par[N][18], in[N], out[N], tsz;
void Dfs(int s, int e) {
in[s] = ++tsz;
par[s][0] = e;
for (int i = 1; i < 18; i++) par[s][i] = par[par[s][i - 1]][i - 1];
for (int u : g[s]) {
if (u == e) continue;
Dfs(u, s);
}
out[s] = tsz;
}
bool Ancestor(int u, int v) {
return in[u] <= in[v] && out[v] <= out[u];
}
int Lca(int u, int v) {
if (Ancestor(u, v)) return u;
if (Ancestor(v, u)) return v;
for (int i = 17; i >= 0; i--) {
if (par[u][i] && !Ancestor(par[u][i], v)) u = par[u][i];
}
return par[u][0];
}
int c[N], predak[N];
vector<int> boja[N];
set<int> koji[N];
void Dfs1(int s, int e) {
for (int u : g[s]) {
if (u == e) continue;
if (c[s] != c[u] && Ancestor(predak[c[u]], s)) koji[c[u]].insert(c[s]);
Dfs1(u, s);
}
}
vector<int> a[N], b[N], order;
int visited[N], id[N], szk[N], brk;
void Dfs2(int s) {
if (visited[s] == 1) return;
visited[s] = 1;
for (int u : a[s]) {
Dfs2(u);
}
order.push_back(s);
}
void Dfs3(int s) {
if (id[s] > 0) return;
id[s] = brk;
szk[brk] += 1;
for (int u : b[s]) {
Dfs3(u);
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n, k;
cin >> n >> k;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
Dfs(1, 0);
for (int i = 1; i <= n; i++) {
cin >> c[i];
boja[c[i]].push_back(i);
}
for (int i = 1; i <= k; i++) {
predak[i] = boja[i][0];
for (int j = 1; j < boja[i].size(); j++) predak[i] = Lca(predak[i], boja[i][j]);
}
Dfs1(1, 0);
for (int i = 1; i <= k; i++) {
for (int j : koji[i]) {
a[i].push_back(j);
b[j].push_back(i);
}
}
for (int i = 1; i <= k; i++) {
if (visited[i] == 0) {
Dfs2(i);
}
}
reverse(order.begin(), order.end());
for (int i : order) {
if (id[i] == 0) {
brk += 1;
Dfs3(i);
}
}
vector<int> cnt(brk + 1);
for (int i = 1; i <= k; i++) {
for (int j : a[i]) {
if (id[i] != id[j]) {
cnt[id[i]] += 1;
}
}
}
int ans = inf;
for (int i = 1; i <= brk; i++) if (cnt[i] == 0) smin(ans, szk[i] - 1);
cout << ans << en;
return 0;
}
