#include "bits/stdc++.h"
using namespace std;
#ifdef Nero
#include "Deb.h"
#else
#define deb(...)
#endif
const int N = 2e5 + 5;
int pr[N];
int sz[N];
int tot[N];
int color[N];
bool viscol[N];
bool blocked[N];
vector<int> g[N];
vector<int> ofcolor[N];
void find_sizes(int v, int p, int flag) {
sz[v] = 1;
pr[v] = p;
if (flag == 1) {
ofcolor[color[v]].push_back(v);
} else if (flag == -1) {
ofcolor[color[v]].pop_back();
}
for (int u : g[v]) {
if (!blocked[u] && u != p) {
find_sizes(u, v, flag);
sz[v] += sz[u];
}
}
}
int find_centroid(int v, int p, int x) {
for (int u : g[v]) {
if (!blocked[u] && u != p && sz[u] > x / 2) {
return find_centroid(u, v, x);
}
}
return v;
}
int decompose(int root) {
find_sizes(root, root, 0);
int centroid = find_centroid(root, root, sz[root]);
find_sizes(centroid, centroid, 1);
queue<int> que;
viscol[color[centroid]] = true;
vector<int> used = {color[centroid]};
for (int i : ofcolor[color[centroid]]) {
que.push(i);
}
while (!que.empty()) {
int v = que.front();
que.pop();
if (!viscol[color[pr[v]]]) {
used.push_back(color[pr[v]]);
viscol[color[pr[v]]] = true;
for (int i : ofcolor[color[pr[v]]]) {
que.push(i);
}
}
}
bool ok = true;
for (int i : used) {
viscol[i] = false;
ok &= ((int) ofcolor[i].size() == tot[i]);
}
find_sizes(centroid, centroid, -1);
int ret = (ok ? (int) used.size() : N);
blocked[centroid] = true;
for (int u : g[centroid]) {
if (!blocked[u]) {
ret = min(ret, decompose(u));
}
}
return ret;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, k;
cin >> n >> k;
for(int i = 0; i < n - 1; ++i) {
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
for (int i = 1; i <= n; ++i) {
cin >> color[i];
tot[color[i]]++;
}
int ans = decompose(1);
cout << ans - 1 << '\n';
return 0;
}
