#include <bits/stdc++.h>
using i64 = long long;
#ifdef DEBUG
#include "debug.h"
#else
#define debug(...) void(23)
#endif
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
int N, K;
std::cin >> N >> K;
std::vector<std::vector<int>> adj(N);
for (int i = 1; i < N; ++i) {
int U, V;
std::cin >> U >> V;
--U, --V;
adj[U].emplace_back(V);
adj[V].emplace_back(U);
}
std::vector<int> C(N);
for (int i = 0; i < N; ++i) {
std::cin >> C[i];
--C[i];
}
std::vector<std::vector<int>> gs(K);
for (int i = 0; i < N; ++i) {
gs[C[i]].emplace_back(i);
}
int ans = K;
std::vector<int> par(N);
std::vector<int> cnt(K);
std::vector<int> vis(K);
std::vector<int> siz(N);
std::vector<int> act(N, true);
auto calc_siz = [&](auto&& self, int v) -> void {
siz[v] = 1;
cnt[C[v]] = 0;
vis[C[v]] = false;
for (auto u : adj[v]) {
if (u == par[v] || !act[u]) {
continue;
}
par[u] = v;
self(self, u);
siz[v] += siz[u];
}
};
auto get_centroid = [&](auto&& self, int v, int tot) -> int {
for (auto u : adj[v]) {
if (u == par[v] || !act[u]) {
continue;
}
if (siz[u] * 2 > tot) {
return self(self, u, tot);
}
}
return v;
};
auto dfs = [&](auto&& self, int v) -> void {
cnt[C[v]] += 1;
for (auto u : adj[v]) {
if (u == par[v] || !act[u]) {
continue;
}
par[u] = v;
self(self, u);
}
};
auto decomp = [&](auto&& self, int v) -> void {
par[v] = -1;
calc_siz(calc_siz, v);
v = get_centroid(get_centroid, v, siz[v]);
par[v] = -1;
dfs(dfs, v);
debug(v);
std::queue<int> que;
int now = 0;
auto insert_color = [&](auto c) -> void {
if (vis[c]) {
return;
}
vis[c] = true;
if (cnt[c] != gs[c].size()) {
now = K;
return;
}
now += 1;
for (auto i : gs[c]) {
que.emplace(i);
}
};
insert_color(C[v]);
while (!que.empty()) {
auto i = que.front();
que.pop();
if (i != v) {
insert_color(C[par[i]]);
}
}
debug(now);
ans = std::min(ans, now - 1);
act[v] = false;
for (auto u : adj[v]) {
if (!act[u]) {
continue;
}
self(self, u);
}
};
decomp(decomp, 0);
std::cout << ans << '\n';
return 0;
}
