#include<bits/stdc++.h>
using namespace std;
#define pb push_back
using pii=pair<int,int>;
const int lim=2e5+100;
vector<int>v[lim];
int a[lim];
int ans;
int tin[lim],tout[lim],tt=1;
int parent[lim];
void dfs(int node,int par){
parent[node]=par;
tin[node]=tt++;
for(int j:v[node]){
if(j==par)continue;
dfs(j,node);
}
tout[node]=tt-1;
}
struct comp{
bool operator()(int x,int y)const {
return tin[x]<tin[y];
}
};
set<int,comp>st;
int vis[lim];
int tot;
int sz[lim];
int sbs(int node,int par){
sz[node]=1;
for(int j:v[node]){
if(j==par||vis[j])continue;
sz[node]+=sbs(j,node);
}
return sz[node];
}
int findcen(int node,int par){
for(int j:v[node]){
if(j!=par&&!vis[j]&&2*sz[j]>tot)return findcen(j,node);
}
return node;
}
unordered_map<int,int>cnt;
unordered_set<int>taken;
vector<int>guys[lim];
void calccnt(int node,int par){
cnt[a[node]]++;
for(int j:v[node]){
if(j==par||vis[j])continue;
calccnt(j,node);
}
}
void decomp(int node){
tot=sbs(node,0);
node=findcen(node,0);
cnt.clear();
calccnt(node,0);
if(cnt[a[node]]==guys[a[node]].size()){
taken.clear();
st.clear();
queue<int>need;
unordered_set<int>cols;
cols.insert(a[node]);
for(int j:guys[a[node]]){
need.push(j);
}
int head=need.front();
need.pop();
taken.insert(head);
// cerr<<"head is "<<head<<'\n';
// cerr<<"can get ";
for(int j:v[head]){
if(j!=parent[head]&&!vis[j]&&!taken.count(j)){
// cerr<<j<<' ';
st.insert(j);
}
}
// cerr<<'\n';
int cant=0;
while(need.size()&&!cant){
int totake=need.front();
need.pop();
while(!taken.count(totake)&&!cant){
if(!st.size()||tin[totake]<tin[*st.begin()]||tin[totake]>tout[*st.rbegin()]){
if(!parent[head]||vis[parent[head]]){
cant=1;
break;
}else{
head=parent[head];
if(cnt[a[head]]!=guys[a[head]].size()){
cant=1;
break;
}
if(!cols.count(a[head])){
cols.insert(a[head]);
for(int j:guys[a[head]]){
need.push(j);
}
}
// cerr<<"took old parent "<<head<<'\n';
taken.insert(head);
for(int j:v[head]){
if(j!=parent[head]&&!vis[j]&&!taken.count(j)){
st.insert(j);
}
}
}
}else{
auto p=prev(st.upper_bound(totake));
int guy=*p;
if(cnt[a[guy]]!=guys[a[guy]].size()){
cant=1;
break;
}
if(!cols.count(a[guy])){
cols.insert(a[guy]);
for(int j:guys[a[guy]]){
need.push(j);
}
}
// cerr<<"took old fashion "<<guy<<'\n';
taken.insert(guy);
for(int j:v[guy]){
if(j!=parent[guy]&&!vis[j]&&!taken.count(j)){
st.insert(j);
}
}
}
}
}
if(!cant){
// cerr<<"found one\n";
// cerr<<"cols :: ";
// for(int i:cols)cerr<<i<<' ';
// cerr<<'\n';
// cerr<<"taken :: ";
// for(int i:taken)cerr<<i<<' ';
// cerr<<'\n';
ans=min<int>(ans,cols.size()-1);
}
}
vis[node]=1;
for(int j:v[node]){
if(!vis[j]){
decomp(j);
}
}
}
int main(){
int n,__;
cin>>n>>__;
for(int i=0;i<n-1;i++){
int x,y;
cin>>x>>y;
v[x].pb(y);
v[y].pb(x);
}
for(int i=1;i<=n;i++){
cin>>a[i];
guys[a[i]].pb(i);
}
ans=n;
dfs(1,0);
decomp(1);
cout<<ans<<'\n';
}
