// author : thembululquaUwU
// 3.9.2024
#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
#define endl '\n'
using namespace std;
using ll = long long;
using ii = pair <int, int>;
using vi = vector <int>;
const int N = 2e5 + 5;
const int mod = 1e9 + 7;
const int LG = 20;
void maxl(auto &a, auto b) {a = max(a, b);}
void minl(auto &a, auto b) {a = min(a, b);}
struct LCA{
vi t_in, t_out, _lg, high;
vector <vi> euler, adj;
int cnt = 0, n, root;
#define rz resize
void rz(int _n, int _root){
n = _n, root = _root;
t_in.rz(n + 1), t_out.rz(n + 1);
euler.rz(3 * n + 1), _lg.rz(3 * n + 1);
adj.rz(n + 3), high.rz(n + 3, 1);
for (int i = 1; i <= 3 * n; ++ i) _lg[i] = log2(i);
}
void add(int u, int v){adj[u].pb(v); adj[v].pb(u);}
void dfs(int u, int p = 0){
t_in[u] = ++ cnt; euler[cnt].pb(u);
for (int v : adj[u]) if(v ^ p) {
high[v] = high[u] + 1;
dfs(v, u); euler[++ cnt].pb(u);
}
t_out[u] = cnt;
}
int check(int u, int v) {return t_in[u] <= t_in[v] && t_out[v] <= t_out[u];}
int min_by_time(int u, int v) {return (t_in[u] < t_in[v] ? u : v);}
void init(){
dfs(root);
for (int lg = 1; lg < LG; ++lg) {
for (int i = 1; i + (1 << lg) - 1 <= cnt; ++i)
euler[i].pb(min_by_time(euler[i][lg - 1], euler[i + (1 << lg - 1)][lg - 1]));
}
}
int get(int u, int v) {
int L = min(t_in[u], t_in[v]);
int R = max(t_out[u], t_out[v]);
int lg = _lg[R - L + 1];
return min_by_time(euler[L][lg], euler[R - (1 << lg) + 1][lg]);
}
int dist(int u, int v){
int lc = get(u, v);
return high[u] + high[v] - 2 * high[lc];
}
} pqh;
int n, k, last[N], par[N];
vi badj[N], nadj[N * LG];
int to[N][LG], idx[N][LG], nvex;
void dfs(int u = 1, int p = 0){
par[u] = p;
to[u][0] = u, idx[u][0] = ++ nvex;
//cout << u << ' ' << 0 << ' ' << nvex << endl;
for (int j = 1; j < LG; ++ j){
int nxt = par[to[u][j - 1]];
if (!nxt || !idx[nxt][j - 1]) break;
to[u][j] = to[nxt][j - 1], idx[u][j] = ++ nvex;
//cout << u << ' ' << j << ' ' << nvex << endl;
nadj[nvex].pb(idx[u][j - 1]); nadj[nvex].pb(idx[nxt][j - 1]);
}
for (int v : badj[u]) if (v ^ p) dfs(v, u);
}
void add(int c, int u, int p){
for (int l = LG - 1; l >= 0; -- l){
int t = to[u][l]; if (!t || (par[p] && pqh.check(t, par[p]))) continue;
//if (c == 2) cout << idx[u][l] << endl;
nadj[c].pb(idx[u][l]); u = par[t];
}
}
int num[N * LG], low[N * LG], ti = 0, sz[N * LG], ncom = 0, lab[N * LG];
vector <int> stk;
void vis(int u){
num[u] = low[u] = ++ ti;
stk.pb(u);
for (int v : nadj[u]){
if (num[v]) minl(low[u], num[v]);
else vis(v), minl(low[u], low[v]);
}
if (low[u] == num[u]){
++ ncom; int v;
do {
v = stk.back(); stk.pop_back();
low[v] = num[v] = 1e9;
sz[ncom] += (v <= k);
lab[v] = ncom;
} while (v ^ u);
}
}
void solve(){
cin >> n >> k; pqh.rz(n, 1); nvex = k;
for (int i = 1, u, v; i < n; ++ i){
cin >> u >> v;
badj[u].pb(v); badj[v].pb(u);
pqh.add(u, v);
}
pqh.init(); dfs();
for (int i = 1; i <= n; ++ i){
int c; cin >> c;
nadj[idx[i][0]].pb(c);
if (last[c]) {
int p = pqh.get(i, last[c]);;
add(c, i, p); add(c, last[c], p);
}
last[c] = i;
}
for (int i = 1; i <= nvex; ++ i) if (!num[i]) vis(i);
int ans = k; //cout << lab[1] << ' ' << lab[2] << ' ' << lab[3] << endl;
vector <bool> ck(ncom + 1, true);
for (int i = 1; i <= nvex; ++ i){
for (int j : nadj[i]) {
//cout << i << ' ' << j << endl;
if (lab[i] ^ lab[j]) ck[lab[i]] = false;
}
}
for (int i = 1; i <= ncom; ++ i) if (ck[i]) {
minl(ans, sz[i]); //cout << i << ' ' << sz[i] << endl;
}
cout << ans - 1;
}
int main(){
if (fopen("pqh.inp", "r")){
freopen("pqh.inp", "r", stdin);
freopen("pqh.out", "w", stdout);
}
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int t = 1; // cin >> t;
while (t --) solve();
return 0;
}
