#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
using namespace std;
const int N = 1<<18, M = N * 3;
vector<int> nei[M], adj[M], jda[M], lst[M], scc, ord;
int pr[M], ch[M], col[M], id[M], num[M], tp[M], lca[M], vis[M], lab[M], inv[M], cur;
void Add(int u, int v){
if (v == 0)
v = N + N + 1;
adj[u].push_back(v);
jda[v].push_back(u);
}
void build(int cr = 1){
lab[cr] = cr + N + N;
if (cr >= N){
lab[cr] = inv[cr - N];
return;
}
int lc = cr + cr, rc = lc + 1;
build(rc);
build(lc);
Add(lab[cr], lab[lc]);
Add(lab[cr], lab[rc]);
}
void rangeAdd(int l, int r, int x){
for (l += N - 1, r += N + 1;l + 1 < r; l /= 2, r /= 2){
if (!(l & 1))
Add(x, lab[l + 1]);
if (r & 1)
Add(x, lab[r - 1]);
}
}
void dfs1(int u){
ch[u] = 1;
for (int &i : nei[u]){
nei[i].erase(find(begin(nei[i]), end(nei[i]), u));
dfs1(i);
pr[i] = u;
ch[u] += ch[i];
if (ch[i] > ch[nei[u][0]])
swap(nei[u][0], i);
}
}
void dfs2(int u, int t){
num[u] = ++cur;
inv[cur] = u;
tp[u] = t;
for (int i : nei[u])
dfs2(i, (i == nei[u][0] ? t : i));
}
int LCA(int u, int v){
for (; tp[u] != tp[v]; v = pr[tp[v]]){
if (num[v] < num[u])
swap(u, v);
}
if (num[v] < num[u])
swap(u, v);
return u;
}
void dfs3(int u){
int v = u, t = lca[col[u]];
while (tp[v] != tp[t]){
rangeAdd(num[tp[v]], num[v], u);
v = pr[tp[v]];
}
rangeAdd(num[t], num[v], u);
for (int i : nei[u])
dfs3(i);
}
void dfs4(int u){
vis[u] = 1;
for (int i : adj[u])
if (vis[i] != 1)
dfs4(i);
ord.push_back(u);
}
void dfs5(int u){
vis[u] = 2;
scc.push_back(u);
id[u] = cur;
for (int i : jda[u])
if (vis[i] != 2)
dfs5(i);
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL);
int n, k;
cin>>n>>k;
for (int i=1;i<n;i++){
int a, b;
cin>>a>>b;
nei[a].push_back(b);
nei[b].push_back(a);
}
dfs1(1);
dfs2(1, 1);
for (int i=1;i<=n;i++){
cin>>col[i];
lst[col[i]].push_back(i);
if (lca[col[i]] == 0)
lca[col[i]] = i;
else
lca[col[i]] = LCA(i, lca[col[i]]);
}
for (int i=1;i<=k;i++){
int L = lst[i].back();
for (int j : lst[i])
Add(L, j), L = j;
}
build();
dfs3(1);
for (int i=1;i<=n;i++)
if (vis[i] == 0)
dfs4(i);
if (!vis[N + N + 1])
dfs4(N + N + 1);
int ans = n;
while (ord.size() > 0){
int u = ord.back(); ord.pop_back();
if (vis[u] != 2){
++cur;
scc = {};
dfs5(u);
set<int> st = {0};
bool t = 1;
for (int i : scc){
for (int j : adj[i]){
if (id[j] != cur)
t = 0;
}
st.insert(col[i]);
}
if (t)
ans = min(ans, (int)st.size());
}
}
cout<<max(0, ans - 2)<<endl;
}
