/*input
*/
#include <bits/stdc++.h>
#define pb push_back
#define x first
#define y second
#define all(a) a.begin(), a.end()
#define sz(a) (int)a.size()
#define rd() abs((int)rng())
using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
const int maxn = 2e5 + 100;
const int mod = 1e9 + 7;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
int n, k, color[maxn], vis[maxn], par[maxn], par2[maxn], sub[maxn], color_added[maxn], color_id[maxn], color_cnt[maxn], color_total[maxn];
vector<int>byColor[maxn];
vector<int>colors;
vector<int>adj[maxn];
void dfs(int v) {
sub[v] = 1;
for (int to : adj[v]) {
if (!vis[to] && to != par[v]) {
par[to] = v;
dfs(to);
sub[v] += sub[to];
}
}
}
int get_centroid(int v) {
par[v] = 0;
dfs(v);
int siz = sub[v];
while (true) {
pii mx = {0, 0};
for (int to : adj[v]) {
if (!vis[to] && to != par[v]) {
mx = max(mx, {sub[to], to});
}
}
if (mx.x * 2 > siz) {
v = mx.y;
} else {
return v;
}
}
}
void dfs2(int v, int p) {
par2[v] = p;
if (color_id[color[v]] == -1) {
color_id[color[v]] = sz(colors);
colors.pb(color[v]);
}
for (int to : adj[v]) {
if (!vis[to] && to != p) {
dfs2(to, v);
}
}
}
void dfs3(int v, int p) {
byColor[color_id[color[v]]].pb(v);
++color_cnt[color[v]];
for (int to : adj[v]) {
if (!vis[to] && to != p) {
dfs3(to, v);
}
}
}
int ans = mod;
void solve(int v, int level = 0) {
par[v] = 0;
v = get_centroid(v);
vis[v] = 1;
// cout << "level: " << level << ", vertex: " << v << "\n";
for (int c : colors) {
if (color_id[c] != -1) {
byColor[color_id[c]].clear();
}
color_cnt[c] = 0;
color_id[c] = -1;
color_added[c] = 0;
}
colors.clear();
dfs2(v, 0);
dfs3(v, 0);
queue<int>Q;
Q.push(color[v]);
color_added[color[v]] = 1;
int total_colors = 1;
while (sz(Q)) {
int c = Q.front();
if (color_cnt[c] != color_total[c]) {
total_colors = mod;
}
Q.pop();
for (int u : byColor[color_id[c]]) {
int p = par2[u];
if (p != 0 && !color_added[color[p]]) {
++total_colors;
color_added[color[p]] = 1;
Q.push(color[p]);
}
}
}
ans = min(ans, total_colors - 1);
for (int to : adj[v]) {
if (!vis[to]) {
solve(to, level + 1);
}
}
}
int fast() {
for (int i = 1; i <= k; i++) {
color_total[i] = 0;
color_id[i] = -1;
}
for (int i = 1; i <= n; i++) {
++color_total[color[i]];
vis[i] = 0;
}
ans = mod;
solve(1);
return ans;
}
int main()
{
ios_base::sync_with_stdio(false), cin.tie(0);
cin >> n >> k;
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
adj[a].pb(b);
adj[b].pb(a);
}
for (int i = 1; i <= n; i++) {
cin >> color[i];
}
cout << fast() << "\n";
return 0;
}
