#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#define int long long
#define pii pair<int,int>
#define vi vector<int>
#define ff first
#define ss second
#define sp << " " <<
#define all(x) x.begin(),x.end()
#define big(x) ((int)(x.size()))
using namespace std;
const int MOD = 1e9+7, LIM = 1e9, inf = 2e9,MAXN = 1e6+1;
const int N = 2e5+1;
vi edges[N],cnt(N,0),c(N),saw(N,0),tin(N),tout(N),antitin(N),par(N);
int ans = inf;
vi dad(N),sz(N);
set<int> comps[N];
struct DSU {
DSU(){};
DSU(int nn) {
for (int i=1;i<=nn;i++) {
comps[i].insert(c[i]);
dad[i] = i;
sz[i] = 1;
}
}
int find(int x) {
if (x == dad[x]) return x;
return dad[x] = find(dad[x]);
}
void merge(int a,int b) {
int x = find(a),y = find(b);
if (x == y) return;
if (sz[x] > sz[y]) comps[x].swap(comps[y]);
for (auto it : comps[x]) comps[y].insert(it);
comps[x].clear();
sz[y] = comps[y].size();
dad[x] = y;
}
} dsu;
set<int> places[N];
int timer = 1;
void operate(int a,int b) {
//cout << a sp b << endl;
while (tin[dsu.find(a)] > tin[b]) {
int lmao = par[dsu.find(a)];
//cout << "MRG" sp a sp lmao << '\n';
dsu.merge(a,lmao);
a = lmao;
}
}
void dfs(int node,int p) {
int old = saw[c[node]];
saw[c[node]]++;
tin[node] = timer++;
par[node] = p;
antitin[tin[node]] = node;
for (auto it : edges[node]) {
if (it != p) dfs(it,node);
}
int kirito=saw[c[node]]-old;
//cout << "NODE" sp node << endl;
tout[node] = timer-1;
while (1) {
auto iter = places[c[node]].lower_bound(tin[node]);
if (iter == places[c[node]].end() || *iter > tout[node]) break;
operate(antitin[*iter],node);
places[c[node]].erase(iter);
}
places[c[node]].insert(tin[node]);
if (kirito == cnt[c[node]]) {
//cout << "C" sp node sp c[node] sp dsu.find(node) sp sz[dsu.find(node)] << endl;
ans = min(ans,sz[dsu.find(node)]);
}
}
void solve() {
int n,k;
cin >> n >> k;
//st[find(i)] --> i rengini şu ana kadar maintainlemek için mergelemem gereken adamlar
//cevap: min(st[find(c)].size() when node == lca(c1,c2,c3...))
for (int i=1;i<n;i++) {
int a,b;
cin >> a >> b;
edges[a].push_back(b);
edges[b].push_back(a);
}
for (int i=1;i<=n;i++) {
cin >> c[i];
cnt[c[i]]++;
}
dsu = DSU(n);
dfs(1,1);
cout << ans-1 << '\n';
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef Dodi
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
int t = 1;
//cin >> t;
while (t --> 0) solve();
}
