#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef pair<pii,pii>pi2;
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
vector<int>adj[200005];
int sz[200005];
int lvl[200005];
int color[200005];
int visited[200005];
int ptr=1;
vector<int>storage[200005];
int pp[200005];
void dfs(int index, int par, int l){
sz[index]=1;
visited[index]=ptr;
for(auto it:adj[index]){
if(lvl[it]!=-1) continue;
if(it==par) continue;
pp[it]=index;
dfs(it,index,l);
sz[index]+=sz[it];
}
}
int dfs2(int index, int par, int n){
for(auto it:adj[index]){
if(lvl[it]!=-1) continue;
if(it!=par&&sz[it]>n/2){
return dfs2(it,index,n);
}
}
return index;
}
int n,k;
int ans=0;
void dp(int index, int hold){
queue<int>q;
unordered_set<int>se;
se.insert(color[index]);
for(auto it:storage[color[index]]){
if(visited[it]!=hold) return;
if(it==index) continue;
q.push(it);
}
while(!q.empty()){
int cur=q.front();
q.pop();
int nxt=pp[cur];
if(se.find(color[nxt])!=se.end()) continue;
se.insert(color[nxt]);
for(auto it:storage[color[nxt]]){
if(visited[it]!=hold) return;
q.push(it);
}
}
//show4(se,se);
ans=min(ans,(int)se.size()-1);
}
void build(int index, int par, int l){
dfs(index,par,l);
int k=sz[index];
int cent=dfs2(index,par,k);
if(par==-1) par=cent;
dfs(cent,-1,l);
//show(cent,cent);
dp(cent,ptr);
lvl[cent]=l;
for(auto it:adj[cent]){
if(lvl[it]!=-1) continue;
ptr++;
build(it,cent,l+1);
}
}
void solve(){
cin >> n >> k;
int temp,temp2;
ans=k;
for(int x=0;x<n-1;x++){
cin >> temp >> temp2;
adj[temp].push_back(temp2);
adj[temp2].push_back(temp);
}
for(int x=1;x<=n;x++){
cin >> color[x];
storage[color[x]].push_back(x);
}
memset(lvl,-1,sizeof(lvl));
build(1,-1,0);
cout << ans;
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
//cin >> t;
while(t--){
solve();
}
}
