#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define FOR(i, a, b) for ( int i = a ; i <= b ; i++ )
#define FORD(i, a, b) for (int i = b; i >= a; i --)
#define REP(i, n) for (int i = 0; i < n; ++i)
#define REPD(i, n) for (int i = n - 1; i >= 0; --i)
#define Lg(x) 31 - __builtin_clz(x)
#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int MAX = 2e5 + 5;
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void setupIO(){
#define name "Whisper"
//Phu Trong from Nguyen Tat Thanh High School for gifted student
srand(time(NULL));
cin.tie(nullptr)->sync_with_stdio(false); cout.tie(nullptr);
//freopen(name".inp", "r", stdin);
//freopen(name".out", "w", stdout);
cout << fixed << setprecision(10);
}
template <class X, class Y>
bool minimize(X &x, const Y &y){
X eps = 1e-9;
if (x > y + eps) {x = y; return 1;}
return 0;
}
template <class X, class Y>
bool maximize(X &x, const Y &y){
X eps = 1e-9;
if (x + eps < y) {x = y; return 1;}
return 0;
}
int numNode, numCity;
vector<int> G[MAX];
int C[MAX];
int sz[MAX], del[MAX];
void reSubsize(int u, int p = -1){
sz[u] = 1;
for (int &v : G[u])if (v ^ p){
if (del[v]) continue;
reSubsize(v, u);
sz[u] += sz[v];
}
}
int getCentroid(int u, int p, int siz){
for (int &v : G[u]) if(v ^ p){
if (2 * sz[v] > siz && !del[v]) return getCentroid(v, u, siz);
}
return u;
}
int cnt[MAX], vis[MAX], par[MAX];
vector<int> color[MAX];
void dfs(int u, int p, bool ok){
if (ok){
color[C[u]].push_back(u); par[u] = p;
}
else{
color[C[u]].clear(); vis[C[u]] = 0;
}
for (int&v : G[u]) if(v ^ p){
if (!del[v]) dfs(v, u, ok);
}
}
int ans = INF;
void decompose(int root){
reSubsize(root);
int siz = sz[root];
root = getCentroid(root, -1, siz);
dfs(root, root, 1);
del[root] = 1;
int ret = 0;
bool full = 1;
queue<int> q;
q.emplace(C[root]); vis[C[root]] = 1;
while (!q.empty()){
int current_color = q.front(); q.pop();
if ((int)color[current_color].size() != cnt[current_color]){full = 0; continue;}
for (int &node : color[current_color]){
int p = par[node];
if (!vis[C[p]]){
vis[C[p]] = 1;
q.emplace(C[p]); ++ ret;
}
}
}
dfs(root, root, 0);
if (full) minimize(ans, ret);
for (int &v : G[root]){
if (!del[v]) decompose(v);
}
}
void Whisper(){
cin >> numNode >> numCity;
for (int i = 1; i < numNode; ++i){
int u, v; cin >> u >> v;
G[u].push_back(v);
G[v].push_back(u);
}
for (int i = 1; i <= numNode; ++i){
cin >> C[i];
cnt[C[i]]++;
}
decompose(1);
cout << ans;
}
signed main(){
setupIO();
int Test = 1;
// cin >> Test;
for ( int i = 1 ; i <= Test ; i++ ){
Whisper();
if (i < Test) cout << '\n';
}
}
