#include <bits/stdc++.h>
using namespace std;
#define el "\n"
#define FOR(i,a,b) for(int i = (a), _b = (b); i <= _b; i++)
#define FORD(i,a,b) for(int i = (a), _b = (b); i >= _b; i--)
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define lg(x) __lg(x)
#define alla(a,n) a+1,a+n+1
#define ll long long
#define debug(x) cout << (x) << " ";
#define c_bit(msk) __builtin_popcount(msk)
template <class T> bool maxi(T &x, T y) { if(x < y) { x = y ; return true ;} return false;}
template <class T> bool mini(T &x, T y) { if(x > y) { x = y ; return true ;} return false;}
const int N = 2e5 + 2;
int n, a[N], k;
vector<int> adj[N];
pair<int, int> E[N];
vector<int> pos[N];
void inp()
{
cin >> n >> k;
FOR(i, 1, n - 1) {
int x, y; cin >> x >> y;
E[i] = {x, y};
adj[x].pb(y);
adj[y].pb(x);
}
FOR(i, 1, n) {
cin >> a[i];
pos[a[i]].push_back(i);
}
}
/* Try your best
No regrets */
namespace subtask_1
{
struct DSU
{
int lab[N];
int root(int x)
{
return lab[x] < 0 ? x : lab[x] = root(lab[x]);
}
bool joint(int x, int y)
{
x = root(x); y = root(y);
if(x == y) return 0;
if(lab[x] > lab[y]) swap(x, y);
lab[x] += lab[y];
lab[y] = x;
return 1;
}
} dsu;
bool ok[N];
int temp[N];
int cnt[N];
void slv()
{
int ans = k - 1;
for(int msk = 0; msk < (1 << k); msk++) {
FOR(i, 1, n) temp[i] = a[i];
for(int i = 1; i <= k; i++) ok[i] = 0;
int uwu = 0;
for(int color = 0; color < k; color++) if(msk >> color & 1) {
if(!uwu) uwu = color + 1;
ok[color + 1] = 1;
}
FOR(i, 1, n) if(ok[temp[i]]) temp[i] = uwu;
for(int i = 1; i <= n; i++) dsu.lab[i] = -1;
FOR(i, 1, n - 1) {
int x = E[i].first, y = E[i].second;
if(temp[x] == temp[y] && temp[x] == uwu) {
dsu.joint(x, y);
}
}
for(int i = 1; i <= k; i++) cnt[i] = 0;
for(int i = 1; i <= n; i++) cnt[temp[i]]++;
// for(int i = 1; i <= n; i++) cout << temp[i] << " "; cout << el;
bool oke = 0;
for(int i = 1; i <= n; i++) {
int p = dsu.root(i);
int number = dsu.lab[p];
if(-number == cnt[temp[i]]) {
oke = 1;
break;
}
}
if(oke) {
if(!msk) ans = 0;
else mini(ans, c_bit(msk) - 1);
}
}
cout << ans;
}
}
namespace subtask_2
{
bool have[N];
int h[N], up[N][21];
int tin[N], time = 0;
void dfs(int u, int p)
{
tin[u] = ++time;
up[u][0] = p;
FOR(j, 1, lg(n)) up[u][j] = up[up[u][j - 1]][j - 1];
for(int v : adj[u]) if(v != p) {
h[v] = h[u] + 1;
dfs(v, u);
}
}
int LCA(int u, int v)
{
if(h[u] < h[v]) swap(u, v);
FORD(j, lg(n), 0) if(h[up[u][j]] >= h[v]) u = up[u][j];
if(u == v) return u;
FORD(j, lg(n), 0) if(up[u][j] != up[v][j]) {
u = up[u][j];
v = up[v][j];
}
return up[u][0];
}
vector<int> cur_city;
void connect(int x, int y)
{
int p = LCA(x, y);
while(x != p) {
if(!have[a[x]]) cur_city.push_back(a[x]);
have[a[x]] = 1;
x = up[x][0];
}
while(y != p) {
if(!have[a[y]]) cur_city.push_back(a[y]);
have[a[y]] = 1;
y = up[y][0];
}
if(!have[a[p]]) cur_city.push_back(a[p]);
have[a[p]] = 1;
}
int getAns(int C)
{
cur_city.clear();
cur_city.push_back(C);
have[C] = 1;
for(int id = 0; id < cur_city.size(); id++) {
int x = cur_city[id];
for(int i = 1; i < pos[x].size(); i++) {
connect(pos[x][i], pos[x][i - 1]);
}
}
for(int x : cur_city) have[x] = 0;
return cur_city.size() - 1;
}
void slv()
{
dfs(1, 1);
for(int i = 1; i <= k; i++) {
sort(all(pos[i]), [&](int x, int y){
return tin[x] < tin[y];
});
}
int ans = k - 1;
FOR(i, 1, k) if(!have[i]) {
mini(ans, getAns(i));
}
cout << ans;
}
}
namespace subtask_3
{
int ans = 1e9;
bool vis[N], sz[N];
void dfs_sz(int u, int p)
{
sz[u] = 1;
for(int v : adj[u]) if(v != p && !vis[v]) {
dfs_sz(v, u);
sz[u] += sz[v];
}
}
int centroid(int u, int p, int n)
{
for(int v : adj[u]) if(v != p && !vis[v]) {
if(sz[v] > n / 2) return centroid(v, u, n);
}
return u;
}
int city[N];
set<int> S;
vector<int> city_par[N];
vector<int> cur_city, vec;
int cnt[N], cnt_init[N];
bool have[N];
void dfs(int u, int p)
{
S.insert(city[u]);
cnt[city[u]]++;
if(p) city_par[city[u]].push_back(city[p]);
for(int v : adj[u]) if(v != p && !vis[v]) {
dfs(v, u);
}
}
void solve(int u)
{
vis[u] = 1;
dfs_sz(u, 0);
cur_city.push_back(city[u]);
vec.push_back(city[u]);
dfs(u, 0);
have[city[u]] = 1;
while(cur_city.size()) {
int City = cur_city.back(); cur_city.pop_back();
for(int x : city_par[City]) {
if(have[x]) continue;
have[x] = 1;
cur_city.push_back(x);
vec.push_back(x);
}
}
bool ok = 1;
for(int x : vec) {
if(cnt[x] != cnt_init[x]) {
ok = 0;
break;
}
}
int len = vec.size() - 1;
if(ok) mini(ans, len);
for(int x : S) {
cnt[x] = 0;
have[x] = 0;
city_par[x].clear();
}
S.clear();
cur_city.clear();
vec.clear();
for(int v : adj[u]) if(!vis[v]) {
solve(centroid(v, u, sz[v]));
}
}
void slv()
{
for(int i = 1; i <= n; i++) city[i] = a[i];
for(int i = 1; i <= n; i++) {
cnt_init[city[i]]++;
}
dfs_sz(1, 0);
solve(centroid(1, 0, n));
cout << ans;
}
}
/* Code slowly, think carefully */
main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define __Azul__ "capital_city"
if(fopen(__Azul__".inp", "r")) {
freopen(__Azul__".inp", "r", stdin);
freopen(__Azul__".out", "w", stdout);
}
bool qs = 0;
int T = 1;
if(qs) cin >> T;
while(T--) {
inp();
subtask_3::slv();
}
cerr << "\nTime" << 0.001 * clock() << "s "; return 0;
}
