#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
using namespace std;
const int N = (1<<4) + 1, M = N<<1;
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 or u == v)
return;
// cout<<u<<" "<<v<<endl;
adj[u].push_back(v);
jda[v].push_back(u);
}
void build(int cur = 1){
lab[cur] = cur + N;
if (cur >= N - 1){
lab[cur] = inv[cur - N + 2];
return;
}
int lc = cur + cur, rc = lc + 1;
build(rc);
build(lc);
Add(lab[cur], lab[lc]);
Add(lab[cur], lab[rc]);
// cout<<"done"<<endl;
}
void rangeAdd(int l, int r, int x){
// cout<<x<<' '<<l<<' '<<r<<endl;
l = l + N - 2;
r = r + N - 2;
for (int i=l;i<=r;i++)
Add(x, lab[i]);
return;
Add(x, lab[l]);
Add(x, lab[r]);
l /= 2;
r /= 2;
for (;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]];
// cout<<v<<' '<<"Below"<<endl;
while (tp[v] != tp[t]){
rangeAdd(num[tp[v]], num[v], u);
v = pr[tp[v]];
}
rangeAdd(num[t], num[v], u);
// cout<<v<<' '<<"done"<<endl;
// return;
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(){
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++){
// cout<<num[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]]);
}
// cout<<endl;
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);
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<<ans - 2<<endl;
}
