#include <bits/stdc++.h>
using namespace std;
const int N = 200005;
int siz[N], col[N], cnt[N], par[N];
vector <int> adj[N], own[N]; int res;
bool ban[N], vis[N], mark[N];
void DFS1(int u, int p) {
siz[u] = 1; mark[col[u]] = 0;
cnt[col[u]] = vis[u] = 0;
for (int v : adj[u])
if (v != p && !ban[v]) {
DFS1(v, u);
siz[u] += siz[v];
}
}
int findCen(int u) {
int c = u, p = 0;
while (true) {
bool flag = false;
for (int v : adj[c])
if (v != p && !ban[v] &&
siz[v] * 2 >= siz[u]) {
p = c; c = v;
flag = true; break;
}
if (!flag) break;
}
return c;
}
void BFS1(int u) {
stack <int, vector <int>> st;
st.push(u);
while (st.size()) {
u = st.top(); st.pop();
cnt[col[u]]++;
for (int v : adj[u])
if (v != par[u] && !ban[v]) {
par[v] = u; st.push(v);
}
}
}
int BFS2(int u) {
int cur = 0;
stack <int, vector <int>> st;
st.push(u);
while (st.size()) {
u = st.top(); st.pop();
if (mark[col[u]]) continue;
mark[col[u]] = 1; cur++;
if (cnt[col[u]] !=
int(own[col[u]].size()))
return 1000000000;
for (int v : own[col[u]])
while (par[v] && !vis[v]) {
st.push(v); vis[v] = 1;
v = par[v];
}
}
return cur;
}
void DFS3(int u) {
DFS1(u, 0); u = findCen(u);
par[u] = 0; ban[u] = 1; BFS1(u);
res = min(res, BFS2(u));
for (int v : adj[u])
if (!ban[v]) DFS3(v);
}
int main() {
cin.tie(0)->sync_with_stdio(0);
int n, k; cin >> n >> k;
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
for (int i = 1; i <= n; i++) {
cin >> col[i];
own[col[i]].emplace_back(i);
}
res = k; DFS3(1); cout << res - 1;
}
