#include "bits/stdc++.h"
using namespace std;
void abc() {cout << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
cout << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
while (l != r) cout << *l << " \n"[++l == r];
}
template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) {
return o >> a.first >> a.second;
}
template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) {
return o << '(' << a.first << ", " << a.second << ')';
}
template <typename T> ostream& operator << (ostream& o, vector<T> a) {
bool is = false;
for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;}
return o << '}';
}
#ifdef local
#define test(args...) abc("[" + string(#args) + "]", args)
#else
#define test(args...) void(0)
#endif
using ll = long long;
vector<int> adj[200005];
int city[200005];
vector<int> col[200005];
bool centroid[200005];
int sz[200005], par[200005];
vector<int> curcol[200005];
int ans; int n; int timer;
int seen[200005];
void dfs(int node, int p = -1) {
sz[node] = 1;
curcol[city[node]].push_back(node);
for (auto nxt : adj[node]) {
if (nxt == p || centroid[nxt]) continue;
dfs(nxt, node);
sz[node] += sz[nxt];
par[nxt] = node;
}
}
int find_centroid(int node, int p, int n) {
for (auto nxt : adj[node]) {
if (nxt == p || centroid[nxt]) continue;
if (sz[nxt] * 2 >= n) return find_centroid(nxt, node, n);
}
return node;
}
void clear(int node, int p = -1) {
curcol[city[node]].clear();
for (auto nxt : adj[node]) {
if (nxt == p || centroid[nxt]) continue;
clear(nxt, node);
}
}
void solve(int node) {
dfs(node);
int cent = find_centroid(node, -1, sz[node]);
clear(node);
dfs(cent);
queue<int> q;
q.push(city[cent]);
int ct = 0;
timer++;
seen[city[cent]] = timer;
while (!q.empty()) {
ct++;
auto cur = q.front(); q.pop();
if (curcol[cur].size() != col[cur].size()) {
ct = n; break;
}
for (auto nd : curcol[cur]) {
if (nd == cent) continue;
int p = city[par[nd]];
if (seen[p] == timer) continue;
seen[p] = timer;
q.push(p);
}
}
ans = min(ans, ct - 1);
clear(cent);
centroid[cent] = true;
for (auto nxt : adj[cent]) {
if (!centroid[nxt]) solve(nxt);
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("", "r", stdin);
// freopen("", "w", stdout);
int k; cin >> n >> k; ans = n;
for (int i = 0; i < n-1; i++) {
int a, b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
for (int i = 1; i <= n; i++) {
cin >> city[i];
col[city[i]].push_back(i);
}
solve(1);
cout << ans << "\n";
}
