/*ㅤ∧＿∧
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( つ┳⊃
ε (_)へ⌒ヽﾌ
( ( ･ω･)
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BePhuongSuperSuwi
From TK4 - CHT
ㅤㅤ／ ⌒＼____
/・ ） \
/ノへ ノ /|
ノ ＼\ |/_/_/*/
#include<bits/stdc++.h>
#define task "main"
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define endl '\n'
#define int long long
#define pb push_back
#define fi first
#define se second
#define ii pair<int,int>
#define iii pair<int,ii>
#define iv pair<ii, ii>
#define base 341
#define MASK(i) (1ll << i)
#define oo 1e18
#define isOn(x,i) ((x) & MASK(i))
#define bitOn(x,i) ((x) | MASK(i))
#define bitOff(x,i) ((x) & ~MASK(i))
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define __lcm(a,b) (1ll * ((a) / __gcd((a), (b))) * (b))
using namespace std;
//using namespace __gnu_pbds;
const int maxn = 2e5 + 5;
const int lg = 18;
int n, k, val[maxn];
vector <int> g[maxn], c[maxn];
namespace giai1{
int h[maxn], par[maxn][lg + 2];
void dfs(int u, int p) {
for (int x : g[u]) {
if (x == p) continue;
h[x] = h[u] + 1;
par[x][0] = u;
dfs(x, u);
}
}
int lca(int u, int v) {
if (h[u] < h[v]) swap(u,v);
for (int i = lg; i >= 0; i--) {
if ((h[u] - h[v]) >= MASK(i)) u = par[u][i];
}
if (u == v) return u;
for (int i = lg; i >= 0; i--) {
if (par[u][i] != par[v][i]) {
u = par[u][i];
v = par[v][i];
}
}
return par[u][0];
}
void prelca() {
dfs(1, -1);
for (int j = 1; j <= lg; j++) {
for (int i = 1; i <= n; i++) {
par[i][j] = par[par[i][j-1]][j-1];
}
}
}
bool ok[maxn];
int parent[maxn];
vector <int> cur;
int acs(int u) {
if (parent[u] == u) return u;
else return parent[u] = acs(parent[u]);
}
void join(int u, int v) {
int x = acs(u);
int y = acs(v);
if (x != y) {
parent[x] = y;
}
}
void connect(int u, int v) {
int p = lca(u, v);
while(h[u] > h[p]) {
if (!ok[val[u]]) ok[val[u]] = 1, cur.pb(val[u]);
join(u, par[u][0]);
u = acs(u);
}
while(h[v] > h[p]) {
if (!ok[val[v]]) ok[val[v]] = 1, cur.pb(val[v]);
join(v, par[v][0]);
v = acs(v);
}
if (!ok[val[p]]) ok[val[p]] = 1, cur.pb(val[p]);
}
int mini = oo;
void tinh(int id) {
for (int i = 1; i <= n; i++) parent[i] = i, ok[i] = 0;
cur.clear();
ok[id] = 1;
cur.pb(id);
for (int i = 0; i < cur.size(); i++) {
int x = cur[i];
for (int i = 1; i < c[x].size(); i++) {
connect(c[x][0], c[x][i]);
}
// cout << "!" << x << " ";
}
// cout << id << " " << cur.size() << endl;
// cout << "hi ";
// for (int x : cur)
// cout << x << " ";
// cout << endl;
mini = min(mini, (int)cur.size() - 1);
}
void solve() {
prelca();
for (int i = 1; i <= k; i++) {
tinh(i);
// break;
}
cout << mini;
}
}
namespace giai2{
int tin[maxn], timer = 0, tour[maxn];
void dfs(int u, int p) {
tin[u] = ++timer;
tour[timer] = u;
for (int x : g[u]) {
if (x == p) continue;
dfs(x, u);
}
}
struct fen
{
int n;
vector<int>bit;
fen(){};
fen(int _n):bit(n+1,0),n(_n+1)
{
};
void update(int pos, int v) {
for (int i = pos; i <= n; i += i & -i)
bit[i] += v;
}
int get(int pos) {
int res = 0;
for (int i = pos; i ; i -= i & -i)
res += bit[i];
return res;
}
void updateRange(int l, int r, int v) {
update(l, v);
update(r + 1, -v);
}
int getRange(int l, int r) {
if (l - 1 == 0) return get(r);
return get(r) - get(l - 1);
}
} bit;
int last[maxn];
vector <ii> query[maxn];
void solve() {
dfs(1, -1);
bit = fen(n + 2);
for (int i = 1; i <= k; i++){
int t1 = oo, t2 = -oo;
for (auto x : c[i]) {
t1 = min(t1, tin[x]);
t2 = max(t2, tin[x]);
}
query[t2].pb({t1, i});
// cout << i << " " << t1 << " " << t2 << endl;
// cout << t1 << " " << t2 << endl;
}
int mini = oo;
for (int i = 1; i <= n; i++) {
int col = val[tour[i]];
// cout << col << " ";
if (last[col] > 0)
bit.update(last[col], -1);
bit.update(i, 1);
last[col] = i;
for (auto e : query[i]) {
mini = min(mini, bit.getRange(e.fi, i));
}
}
cout << mini - 1;
}
}
main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
if(fopen(task".inp","r")) {
freopen(task".inp","r",stdin);
freopen(task".out","w",stdout);
}
cin >> n >> k;
for (int i = 1; i < n; i++) {
int l, r;
cin >> l >> r;
g[l].pb(r); g[r].pb(l);
}
for (int i = 1; i <= n; i++) {
cin >> val[i];
c[val[i]].pb(i);
}
// giai2::solve();
if (n <= 2000) giai1::solve();
else giai2::solve();
}
