#include <bits/stdc++.h>
#define F first
#define S second
using namespace std;
using ll = long long;
using pi = pair<int, int>;
using vi = vector<int>;
template<class T> bool ckmin(T& a, T b) { return b < a ? a = b, true : false; }
template<class T> bool ckmax(T& a, T b) { return a < b ? a = b, true : false; }
const int N = 5e5 + 7;
vector<int> g[N];
int c[N], f[N], cnt[N];
map<int, int> s[N];
int l[N], r[N], tt = 0, who[N], par[N], seen[N], bad[N];
void dfs(int u, int p = 0) {
par[u] = p;
l[u] = ++tt;
who[tt] = u;
for (auto v : g[u]) {
if (v == p) continue;
dfs(v, u);
if (s[v].size() > s[u].size()) swap(s[u], s[v]), swap(cnt[u], cnt[v]);
for (auto it : s[v]) {
s[u][it.F] += it.S;
if (s[u][it.F] == f[it.F]) ++cnt[u];
}
}
s[u][c[u]] += 1; if (s[u][c[u]] == f[c[u]]) ++cnt[u];
if (u != 1 && cnt[u] == s[u].size()) bad[u] = 1;
r[u] = tt;
}
pi t[4 * N];
int lazy[4 * N];
void build(int v, int tl, int tr) {
if (tl == tr) {
t[v] = {0, tl};
return;
}
int tm = (tl + tr) / 2;
build(2 * v, tl, tm);
build(2 * v + 1, tm + 1, tr);
t[v] = max(t[2 * v], t[2 * v + 1]);
}
void push(int v, int tl, int tr) {
if (tl < tr) {
lazy[2 * v] += lazy[v];
lazy[2 * v + 1] += lazy[v];
}
t[v].F += lazy[v];
lazy[v] = 0;
}
void add(int v, int tl, int tr, int l, int r, int x) {
push(v, tl, tr);
if (l > tr || r < tl) return;
if (l <= tl && tr <= r) {
lazy[v] += x;
push(v, tl, tr);
return;
}
int tm = (tl + tr) / 2;
add(2 * v, tl, tm, l, r, x);
add(2 * v + 1, tm + 1, tr, l, r, x);
t[v] = max(t[2 * v], t[2 * v + 1]);
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
int n, k; cin >> n >> k;
for (int i = 1; i < n; ++i) {
int a, b; cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
for (int i = 1; i <= n; ++i) cin >> c[i];
for (int i = 1; i <= n; ++i) ++f[c[i]];
dfs(1);
build(1, 1, n);
for (int i = 1; i <= n; ++i) if (bad[i]) add(1, 1, n, l[i], r[i], +1);
int ans = 0;
while (true) {
push(1, 1, n);
pi x = t[1];
if (x.F == 0) break;
++ans;
int u = who[x.S];
while (u != 0 && !seen[u]) {
if (bad[u] == 1) {
bad[u] = 0;
add(1, 1, n, l[u], r[u], -1);
}
seen[u] = 1;
u = par[u];
}
}
cout << (ans + 1) / 2 << "\n";
}
