/// ITNOG
#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define F first
#define S second
#define pb push_back
#define ppb pop_back
#define fast_io ios::sync_with_stdio(false);cin.tie(NULL);
#define file_io freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);
#define FOR(i,k,n) for(int i = k; i < n; ++ i)
#define debf cout<<"(0-0)\n";
#define all(x) x.begin(), x.end()
#define dec(x) cout << fixed << setprecision(x);
#define pf push_front
#define ppf pop_front
#define dash " ------- "
#define what(x) cerr << #x << " is " << x << endl;
#define eb emplace_back
//#define int short int
#define int long long
#define sz(s) (int) (s.size())
#define fl cout.flush()
using namespace std;
//using namespace __gnu_pbds;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <int, pii> pip;
typedef pair <pii, int> ppi;
typedef pair <ll, ll> pll;
typedef unsigned long long ull;
typedef long double ld;
template <class T> using max_heap = priority_queue <T, vector <T>, less <T> >;
template <class T> using min_heap = priority_queue <T, vector <T>, greater <T> >;
//template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
constexpr int MOD = 1e9 + 7, N = 2e5 + 8, M = 1e6, SQ = 600, INF = 1e15 + 8, LGN = 22, mod = 998244353, P = 131113;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
bool mark[N];
int n, k, col[N], st[N], xxx, sz;
vector <int> adj[N];
vector <int> v[N];
bool dfs (int u, int par = -1){
bool ok = false;
if (col[u] == xxx){
ok = true;
}
for (int i : adj[u]){
if (i != par){
ok |= dfs (i, u);
}
}
if (ok){
if (col[u] != xxx){
v[xxx].pb(col[u]);
}
}
return ok;
}
void dfs2 (int u){
mark[u] = true;
//cout << xxx + 1 << " " << u + 1 << '\n';
++ sz;
for (int i : v[u]){
if (!mark[i]){
dfs2 (i);
}
}
return;
}
int32_t main(){
fast_io;
cin >> n >> k;
FOR (i, 0, n - 1){
int aa, bb;
cin >> aa >> bb;
adj[--aa].pb(--bb);
adj[bb].pb(aa);
}
FOR (i, 0, n){
cin >> col[i];
st[--col[i]] = i;
}
for (int i = 0; i < k; ++ i){
xxx = i;
dfs (st[i]);
sort (all(v[xxx]));
v[xxx].resize(unique(all(v[xxx])) - v[xxx].begin());
}
//cout << "--- " << v[2].size() << " " << v[2].back() + 1 << '\n';
int ans = 0;
ans = 1000000;
for (int i = 0; i < k; ++ i){
fill (mark, mark + 2008, false);
sz = 0;
xxx = i;
dfs2 (i);
ans = min (ans, sz - 1);
}
cout << ans;
return 0;
}
// Yesterday is history
// Tomorrow is a mystery
// but today is a gift
// That is why it is called the present
