#include <bits/stdc++.h>
#define fr first
#define sc second
#define pii pair<int, int>
#define pb push_back
#define szof(s) (int)s.size()
#define all(s) s.begin(), s.end()
#define fastInp ios_base::sync_with_stdio(0); cin.tie(0);
#define ll long long
template<class T>void chmax(T &a, T b){if (a < b)a = b;}
template<class T>void chmin(T &a, T b){if (b < a)a = b;}
using namespace std;
const int MAXN = (int)2e5 + 5;
const int INF = 1e9;
const int L = 20;
int n, k;
vector <int> g[MAXN];
int c[MAXN];
int pr[MAXN][L + 1];
int tin[MAXN], tout[MAXN], tiktak = 0;
set <int> colors;
vector <int> color_comp[MAXN];
void precalc(int v, int par) {
tin[v] = ++tiktak;
pr[v][0] = par;
for (int lv = 1; lv <= L; lv++) {
pr[v][lv] = pr[pr[v][lv - 1]][lv - 1];
}
for (int to : g[v]) {
if (to != par) {
precalc(to, v);
}
}
tout[v] = tiktak;
}
bool father(int a, int b) {
return tin[a] <= tin[b] && tout[b] <= tout[a];
}
int get_lca(int a, int b) {
if (father(a, b)) {
return a;
}
if (father(b, a)) {
return b;
}
for (int lv = L; lv >= 0; lv--) {
if (!father(pr[a][lv], b)) {
a = pr[a][lv];
}
}
return pr[a][0];
}
int get_lca(vector <int> &vec) {
int lca = vec[0];
for (int i = 1; i < szof(vec); i++) {
lca = get_lca(lca, vec[i]);
}
return lca;
}
int cur[MAXN];
int used[MAXN], used_id = 1;
void up_dfs(vector <int> &vec, int v, int root) {
if (used[v] == used_id) {
return;
}
used[v] = used_id;
vec.pb(v);
if (v != root) {
up_dfs(vec, pr[v][0], root);
}
}
void relax(vector <int> &comp) {
used_id++;
vector <int> res;
int lca = get_lca(comp);
for (int v : comp) {
up_dfs(res, v, lca);
}
comp = res;
}
struct Subtask_1_2_Solve {
Subtask_1_2_Solve () {
}
void run() {
precalc(1, 1);
int ans = INF;
for (int cur_color : colors) {
for (int i = 1; i <= n; i++) {
cur[i] = c[i];
}
vector <int> comp;
for (int i = 1; i <= n; i++) {
if (c[i] == cur_color) {
comp.pb(i);
}
}
int cur_ans = 0;
while (1) {
relax(comp);
bool ok = 1;
set <int> new_colors;
for (int v : comp) {
ok &= (cur[v] == cur_color);
if (cur[v] != cur_color) {
new_colors.insert(cur[v]);
}
}
if (ok) {
break;
}
else {
for (int el : new_colors) {
cur_ans++;
for (int v : color_comp[el]) {
comp.pb(v);
cur[v] = cur_color;
}
}
continue;
}
}
chmin(ans, cur_ans);
}
cout << ans << endl;
}
};
struct Line_Solve {
int l[MAXN], r[MAXN];
Line_Solve () {
fill(l, l + MAXN, INF);
fill(r, r + MAXN, -INF);
}
struct Point {
int x, type;
Point () {
}
Point (int x_, int type_) {
x = x_, type = type_;
}
const bool operator < (const Point &other) {
return x < other.x;
}
};
void run() {
vector <Point> vec;
for (int i = 1; i <= n; i++) {
chmin(l[c[i]], i);
chmax(r[c[i]], i);
}
for (int i = 1; i <= k; i++) {
vec.pb(Point(l[c[i]], 1));
vec.pb(Point(r[c[i]], -1));
}
sort(all(vec));
int cnt = 0;
set <int> segment;
int ans = INF;
for (auto el : vec) {
int x = el.x;
int type = el.type;
cnt += type;
segment.insert(c[x]);
if (cnt == 0) {
chmin(ans, szof(segment) - 1);
segment.clear();
}
}
cout << ans << endl;
}
};
signed main() {
fastInp;
cin >> n >> k;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
g[u].pb(v);
g[v].pb(u);
}
for (int i = 1; i <= n; i++) {
cin >> c[i];
colors.insert(c[i]);
color_comp[c[i]].pb(i);
}
if (n <= 2000) {
Subtask_1_2_Solve T;
T.run();
return 0;
} else {
Line_Solve T;
T.run();
return 0;
}
}
/*
12 4
7 9
1 3
4 6
2 4
10 12
1 2
2 10
11 1
2 8
5 3
6 7
3
1
1
2
4
3
3
2
2
3
4
4
*/
