// ~~ icebear ~~
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
template<class T>
bool minimize(T &a, const T &b) {
if (a > b) return a = b, true;
return false;
}
template<class T>
bool maximize(T &a, const T &b) {
if (a < b) return a = b, true;
return false;
}
#define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
#define FORR(i,a,b) for(int i=(a); i>=(b); --i)
#define REP(i, n) for(int i=0; i<(n); ++i)
#define RED(i, n) for(int i=(n)-1; i>=0; --i)
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define task "gen"
/*END OF TEMPLATE. ICEBEAR AND THE CAT WILL WIN VOI26 */
const int MOD = 1e9 + 7;
const int inf = 1e9 + 27092008;
const ll INF = 1e18 + 27092008;
const int N = 2e5 + 5;
int n, k;
vector<int> G[N], town[N];
int par[N][20], h[N], city[N];
bool have[N];
struct DisjointSet {
vector<int> lab;
DisjointSet(int n = 0): lab(n + 5, -1) {}
int root(int v) {
return lab[v] < 0 ? v : lab[v] = root(lab[v]);
}
bool unite(int u, int v) {
u = root(u); v = root(v);
if (u == v) return false;
if (h[u] > h[v]) swap(u, v);
lab[v] = u;
return true;
}
} dsu;
void dfs(int u) {
for(int v : G[u]) if (v != par[u][0]) {
par[v][0] = u;
h[v] = h[u] + 1;
dfs(v);
}
}
int LCA(int u, int v) {
if (h[u] < h[v]) swap(u, v);
int s = h[u] - h[v];
RED(j, 20) if (BIT(s, j))
u = par[u][j];
if (u == v) return u;
RED(j, 20) if (par[u][j] != par[v][j]) {
u = par[u][j];
v = par[v][j];
}
return par[u][0];
}
vector<int> cur_city;
void connect(int u, int v) {
int p = LCA(u, v);
// cerr << u << ' ' << v << ' ' << p << '\n';
while(h[u] > h[p]) {
if (!have[city[u]]) cur_city.pb(city[u]);
have[city[u]] = true;
dsu.unite(u, par[u][0]);
u = dsu.root(u);
}
while(h[v] > h[p]) {
if (!have[city[v]]) cur_city.pb(city[v]);
have[city[v]] = true;
dsu.unite(v, par[v][0]);
v = dsu.root(v);
}
if (!have[city[p]]) cur_city.pb(city[p]);
have[city[p]] = true;
if (p > 1) dsu.unite(p, par[p][0]);
}
int get_merge(int C) {
dsu = DisjointSet(n);
cur_city.clear();
cur_city.pb(C);
have[C] = true;
REP(k, (int)cur_city.size()) {
int X = cur_city[k];
FOR(i, 1, (int)town[X].size() - 1) connect(town[X][0], town[X][i]);
}
for(int X : cur_city) have[X] = false;
return (int)cur_city.size() - 1;
}
void init(void) {
cin >> n >> k;
FOR(i, 2, n) {
int u, v;
cin >> u >> v;
G[u].pb(v);
G[v].pb(u);
}
FOR(i, 1, n) {
cin >> city[i];
town[city[i]].pb(i);
}
}
void process(void) {
h[1] = 1;
dfs(1);
FOR(j, 1, 19) FOR(i, 1, n) par[i][j] = par[par[i][j - 1]][j - 1];
int ans = inf;
FOR(i, 1, k) if (!have[i])
minimize(ans, get_merge(i));
cout << ans;
cerr << ans;
// cerr << get_merge(2) << '\n';
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int tc = 1;
// cin >> tc;
while(tc--) {
init();
process();
}
return 0;
}
