#include <bits/stdc++.h>
int main() {
using namespace std;
ios_base::sync_with_stdio(0);
int n, k;
cin >> n >> k;
vector<vector<int>> adj(n);
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
--u, --v;
adj[u].push_back(v);
adj[v].push_back(u);
}
vector<int> c(n);
vector<int> count(n);
for (int i = 0; i < n; i++)
cin >> c[i], c[i]--, count[c[i]]++;
vector<bool> vis(n);
vector<int> sub(n);
function<void(int, int)> dfs_size = [&](int src, int par) {
sub[src] = 1;
for (int nxt : adj[src]) {
if (nxt == par || vis[nxt])
continue;
dfs_size(nxt, src);
sub[src] += sub[nxt];
}
};
auto get_centroid = [&](int src) -> int {
dfs_size(src, -1);
int num = sub[src];
int par = -1;
do {
int go = -1;
for (int nxt : adj[src]) {
if (nxt == par || vis[nxt])
continue;
if (sub[nxt] * 2 > num)
go = nxt;
}
par = src;
src = go;
} while (src != -1);
return par;
};
const int INF = 1e9;
int ans = INF;
map<int, vector<int>> colors;
map<int, int> parent;
set<int> done;
list<int> que;
function<void(int)> solve = [&](int vert) {
colors.clear();
parent.clear();
done.clear();
que.clear();
int root = get_centroid(vert);
function<void(int, int)> dfs_precompute = [&](int src, int par) {
parent[src] = par;
colors[c[src]].push_back(src);
for (int nxt : adj[src]) {
if (nxt == par || vis[nxt])
continue;
dfs_precompute(nxt, src);
}
};
dfs_precompute(root, -1);
int tot = 0;
auto add_color = [&](int col) {
if (done.count(col))
return;
tot++;
done.insert(col);
for (int v : colors[col]) {
que.push_back(v);
}
};
add_color(c[root]);
while (!que.empty()) {
int top = que.front();
que.pop_front();
int par = parent[top];
if (par != -1)
add_color(c[par]);
}
bool ok = true;
for (int x : done)
if ((int) colors[x].size() != count[x])
ok = false;
if (ok)
ans = min(ans, tot - 1);
vis[root] = true;
for (int nxt : adj[root]) {
if (vis[nxt])
continue;
solve(nxt);
}
};
solve(0);
cout << ans << '\n';
return 0;
}
