// https://oj.uz/problem/view/JOI20_capital_city
#include <bits/stdc++.h>
using namespace std;
namespace std {
template <class Fun>
class y_combinator_result {
Fun fun_;
public:
template <class T>
explicit y_combinator_result(T &&fun) : fun_(std::forward<T>(fun)) {}
template <class... Args>
decltype(auto) operator()(Args &&...args) {
return fun_(std::ref(*this), std::forward<Args>(args)...);
}
};
template <class Fun>
decltype(auto) y_combinator(Fun &&fun) {
return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
}
/* Example
auto fun = y_combinator([&](auto self, int x) -> void {
self(x + 1);
});
*/
} // namespace std
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(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].emplace_back(v);
adj[v].emplace_back(u);
}
vector<int> c(n);
for (int i = 0; i < n; i++) cin >> c[i], c[i]--;
vector<int> d(n);
vector<vector<int>> up(__lg(n) + 1, vector<int>(n));
vector<vector<int>> rmq(__lg(n) + 1, vector<int>(n));
vector<vector<int>> g(k);
vector<vector<int>> rg(k);
auto dfs = y_combinator([&](auto self, int u, int p) -> void {
up[0][u] = p;
rmq[0][u] = c[u];
for (int i = 1; i <= __lg(n); i++) {
up[i][u] = up[i - 1][up[i - 1][u]];
if (up[i - 1][u] == u) continue;
rmq[i][u] = g.size();
g.emplace_back(vector<int>({rmq[i - 1][u], rmq[i - 1][up[i - 1][u]]}));
}
for (int v : adj[u]) {
if (v == p) continue;
d[v] = d[u] + 1;
self(v, u);
}
});
auto lca = [&](int group_id, int x, int y) {
if (d[x] < d[y]) swap(x, y);
for (int i = __lg(n); i >= 0; i--) {
if (d[up[i][x]] >= d[y]) {
g[group_id].emplace_back(rmq[i][x]);
x = up[i][x];
}
}
if (x == y) {
g[group_id].emplace_back(rmq[0][x]);
return x;
}
for (int i = __lg(n); i >= 0; i--) {
if (up[i][x] != up[i][y]) {
g[group_id].emplace_back(rmq[i][x]);
g[group_id].emplace_back(rmq[i][y]);
x = up[i][x], y = up[i][y];
}
}
g[group_id].emplace_back(rmq[0][x]);
g[group_id].emplace_back(rmq[1][y]);
return up[0][x];
};
vector<vector<int>> group(k);
for (int i = 0; i < n; i++) group[c[i]].emplace_back(i);
dfs(0, 0);
for (int i = 0; i < k; i++) {
int top = group[i][0];
for (int j : group[i]) top = lca(i, top, j);
}
int N = g.size();
vector<int> low(N), num(N);
int timer = 0;
stack<int> st;
int M = 0;
vector<int> comp(N);
vector<int> cnt;
auto dfs2 = y_combinator([&](auto self, int u) -> void {
low[u] = num[u] = ++timer;
st.emplace(u);
for (int v : g[u]) {
if (num[v]) {
low[u] = min(low[u], num[v]);
} else {
self(v);
low[u] = min(low[u], low[v]);
}
}
if (low[u] == num[u]) {
int v = -1;
cnt.emplace_back(0);
do {
v = st.top();
comp[v] = M;
st.pop();
num[v] = low[v] = N + 1;
cnt[M] += v < k;
} while (v != u);
M++;
}
});
for (int i = 0; i < N; i++) {
if (!num[i]) dfs2(i);
}
for (int i = 0; i < N; i++) {
for (int j : g[i]) {
if (comp[i] == comp[j]) continue;
cnt[comp[i]] = n;
}
}
int res = k;
for (int i = 0; i < k; i++) {
if (cnt[comp[i]]) res = min(res, cnt[comp[i]] - 1);
}
cout << res;
}
