#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
void print(long double t) {cerr << t;}
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T> void print(T v[],T n) {cerr << "["; for(int i = 0; i < n; i++) {cerr << v[i] << " ";} cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
// for random generations
mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
// mt19937 myrand(131);
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
long long ka() {
long long x = 0;
bool z = false;
while (1)
{
char y = getchar();
if (y == '-')
z = true;
else if ('0' <= y && y <= '9')
x = x * 10 + y - '0';
else
{
if (z)
x *= -1;
return x;
}
}
}
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
fastIO();
if (str != "") {
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 2e5 + 10;
vector<int> adj[N], qq[N];
bool used[N], vis[N];
int n, k, ans, curr, cc[N];
queue<int> q;
void add_group(int group) {
curr++;
for(auto i: qq[group]) {
if(!vis[i]) {
q.push(i);
}
}
used[group] = true;
}
int p[N];
void dfs(int node, int parent) {
p[node] = parent;
for(auto i: adj[node]) {
if(i == parent) continue;
dfs(i, node);
}
}
void go_up(int node) {
if(vis[node]) {
return;
} else if(!used[cc[node]]) {
add_group(cc[node]);
}
node = p[node];
go_up(node);
}
void solve_() {
cin >> n >> k;
for(int i = 1; i <= n - 1; i++) {
int a, b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
for(int i = 1; i <= n; i++) {
int c; cin >> c;
cc[i] = c;
qq[c].push_back(i);
}
ans = k;
for(int i = 1; i <= k; i++) {
if(qq[i].empty()) continue;
vis[qq[i].front()] = true;
curr = 0, add_group(i);
dfs(qq[i].front(), 0);
while(!q.empty()) {
auto u = q.front();
q.pop();
go_up(u);
}
ans = min(ans, curr);
for(int j = 1; j <= k; j++) {
used[j] = false;
}
for(int j = 1; j <= n; j++) {
vis[j] = false;
}
}
cout << ans - 1 << '\n';
}
int main() {
setIO();
auto solve = [&](int test_case)-> void {
while(test_case--) {
solve_();
}
};
int test_cases = 1;
// cin >> test_cases;
solve(test_cases);
return 0;
}
