#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ari2 = array<int, 2>;
using ari3 = array<int, 3>;
using arl2 = array<ll, 2>;
using arl3 = array<ll, 3>;
template <class T> using vt = vector<T>;
#define all(x) begin(x), end(x)
#define size(x) (int((x).size()))
#define REP(a,b,c,d) for(int a=(b);(d)>0?a<=(c):a>=(c);a+=(d))
#define FOR(a,b,c) REP(a,b,c,1)
#define ROF(a,b,c) REP(a,b,c,-1)
struct DSU {
vt<int> uf;
DSU(const int n) : uf(n, -1) {}
int find(const int i) {
return uf[i] < 0 ? i : uf[i] = find(uf[i]);
}
bool unite(int a, int b) {
if ((a = find(a)) == (b = find(b)))
return false;
if (uf[a] > uf[b])
swap(a, b);
uf[a] += uf[b];
uf[b] = a;
return true;
}
void reset(const int i) {
uf[i] = -1;
}
};
signed main() {
#ifndef DEBUG
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
#endif
int N, K;
cin >> N >> K;
vt<vt<int>> adj(N);
FOR(_, 2, N) {
int a, b;
cin >> a >> b, a--, b--;
adj[a].push_back(b);
adj[b].push_back(a);
}
vt<int> C(N), cnt(N);
FOR(i, 0, N-1) {
cin >> C[i], C[i]--;
cnt[C[i]]++;
}
vt<int> dead(N), szs(N), nodes, parent(N);
int ans = N;
auto dfs_szs = [&](auto &&self, const int i, const int p) -> void {
szs[i] = 1;
nodes.push_back(i);
for (const auto &j : adj[i]) {
if (j == p || dead[j])
continue;
self(self, j, i);
szs[i] += szs[j];
}
};
auto centroid = [&](int i, const int n) {
int p = -1;
bool flag = true;
while (flag) {
flag = false;
for (const auto &j : adj[i])
if (j != p && !dead[j] && 2 * szs[j] > n) {
p = i;
i = j;
flag = true;
break;
}
}
return i;
};
auto dfs_par = [&](auto &&self, const int i, const int p) -> void {
parent[i] = p;
for (const auto &j : adj[i])
if (j != p && !dead[j])
self(self, j, i);
};
vt<vt<int>> ind_list(K);
vt<int> seen(N);
DSU uf(K);
auto dfs = [&](auto &&self, const int root) -> void {
dfs_szs(dfs_szs, root, -1);
const int c = centroid(root, szs[root]);
dfs_par(dfs_par, c, -1);
#ifdef DEBUG
cout << "centroid: " << c + 1 << '\n';
#endif
for (const auto &i : nodes)
ind_list[C[i]].push_back(i);
queue<int> qu;
for (const auto &i : ind_list[C[c]])
qu.push(i), seen[i] = 1;
bool good = 1;
int res = 0;
while (size(qu) && good) {
const int i = qu.front();
qu.pop();
good &= size(ind_list[C[i]]) == cnt[C[i]];
if (parent[i] >= 0 && !seen[parent[i]] && uf.unite(C[i], C[parent[i]])) {
res++;
for (const auto &j : ind_list[C[parent[i]]]) {
seen[j] = 1;
qu.push(j);
}
}
}
if (good)
ans = min(ans, res);
for (const auto &i : nodes) {
uf.reset(C[i]);
ind_list[C[i]].clear();
}
nodes.clear();
dead[c] = 1;
for (const auto &j : adj[c])
if (!dead[j])
self(self, j);
};
dfs(dfs, 0);
cout << ans << '\n';
}
