//#pragma GCC optimize("Ofast,unroll-loops,O3")
//#pragma GCC optimize("avx,avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,fma,tune=native")
#include<bits/stdc++.h>
//#include<bits/extc++.h>
//#pragma pack(1)
#define fast ios::sync_with_stdio(0); cin.tie(0);
#define pii pair<int,int>
#define x first
#define y second
#define N 200015
#define C 25
using namespace std;
//using namespace __gnu_pbds;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//typedef tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update> order_multiset;
//typedef tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> order_set;
int n,k;
struct SCC{
vector<int>g[C*N];
vector<pii>edge;
int dfn[C*N],low[C*N],dft=0,boss[C*N],val[C*N];
long long dp[C*N],nscc=0;
bool ins[C*N],vis[C*N];
stack<int>st;
void init(){
edge.clear();
while (!st.empty()) st.pop();
for (int i=0;i<C*N;i++){
dfn[i]=low[i]=boss[i]=val[i]=dp[i]=0;
g[i].clear();
ins[i]=vis[i]=0;
}
}
void add_edge(int i,int j){
// i -> j
g[i].push_back(j);
edge.push_back({i,j});
}
void tarjan(int p){
dfn[p]=low[p]=++dft;
st.push(p); ins[p]=1;
for (auto i:g[p]){
if (!dfn[i]){
tarjan(i);
low[p]=min(low[p],low[i]);
}
else if (ins[i]&&dfn[i]<dfn[p])
low[p]=min(low[p],dfn[i]);
}
if (low[p]==dfn[p]){
nscc++;
// cout<<"find cycle "<<nscc<<" : ";
for (int x=0;x!=p;st.pop()){
x=st.top(); ins[x]=0;
boss[x]=nscc;
if (x<=k) val[nscc]++;
// cout<<x<<" ";
}
// cout<<"val "<<val[nscc]<<'\n';
}
}
void build(){
for (int i=0;i<C*n;i++)
g[i].clear();
for (auto i:edge){
if (boss[i.x]!=boss[i.y]){
// cout<<"edge "<<boss[i.x]<<' '<<boss[i.y]<<'\n';
g[boss[i.x]].push_back(boss[i.y]);
}
}
}
int dfs(int p){
if (vis[p]) return dp[p];
vis[p]=1; dp[p]=val[p];
for (auto i:g[p]){
dp[p]+=dfs(i);
dp[p]=min(dp[p],1000000LL);
}
return dp[p];
}
}scc;
int cap[N],vis[N],son[N],all_col[N],sub_col[N],fa[N],have[N];
vector<int>g[N],path,sub_path;
int get_centroid(int p,int lp,int sz){
for (auto i:g[p]){
if (!vis[i]&&i!=lp&&son[i]>sz/2)
return get_centroid(i,p,sz);
}
return p;
}
int dfs1(int p,int lp){
son[p]=1;
path.push_back(p);
for (auto i:g[p]){
if (!vis[i]&&i!=lp)
son[p]+=dfs1(i,p);
}
return son[p];
}
void dfs2(int p,int lp){
fa[p]=lp;
sub_path.push_back(p);
for (auto i:g[p]){
if (!vis[i]&&i!=lp)
dfs2(i,p);
}
}
void build(int root,int dep){
for (auto i:sub_path){
sub_col[cap[i]]++;
scc.add_edge(dep*n+i,cap[i]);
// cout<<"add_1 "<<dep*n+i<<' '<<cap[i]<<'\n';
}
/*
cout<<"sub_col ";
for (int i=1;i<=k;i++)
cout<<sub_col[i]<<' ';
cout<<'\n';
*/
for (auto i:sub_path){
if (all_col[cap[i]]==sub_col[cap[i]])
continue;
int p=i;
// cout<<"try "<<i<<" "<<cap[i]<<'\n';
scc.add_edge(cap[i],dep*n+fa[p]);
while (!have[p]){
scc.add_edge(cap[i],dep*n+fa[p]);
// cout<<"add_2 "<<cap[i]<<" "<<dep*n+fa[p]<<'\n';
have[p]=1; p=fa[p];
}
}
for (auto i:sub_path)
sub_col[cap[i]]--;
}
void Cut(int p,int lp,int dep){
path.clear();
// cout<<p<<" "<<lp<<" "<<dep<<'\n';
int sz=dfs1(p,lp);
int mid=get_centroid(p,lp,sz);
// cout<<mid<<" : \n";
vis[mid]=1; have[mid]=1;
scc.add_edge(dep*n+mid,cap[mid]);
// cout<<"add1 "<<dep*n+mid<<" "<<cap[mid]<<'\n';
for (auto i:path)
all_col[cap[i]]++;
// cout<<"all_col ";
// for (int i=1;i<=k;i++)
// cout<<all_col[i]<<" ";
// cout<<'\n';
for (auto i:g[mid]){
if (vis[i]) continue;
dfs2(i,mid);
build(i,dep);
sub_path.clear();
}
for (auto i:path){
have[i]=0;
all_col[cap[i]]--;
}
for (auto i:g[mid]){
if (!vis[i])
Cut(i,mid,dep+1);
}
}
signed main(){
fast
cin>>n>>k;
scc.init();
for (int i=1;i<n;i++){
int a,b; cin>>a>>b;
g[a].push_back(b);
g[b].push_back(a);
}
for (int i=1;i<=n;i++)
cin>>cap[i];
Cut(1,0,1);
for (int i=1;i<=k;i++){
if (!scc.dfn[i])
scc.tarjan(i);
}
scc.build();
int ans=1e9;
for (int i=1;i<=k;i++){
// cout<<scc.boss[i]<<" "<<scc.dfs(scc.boss[i])<<'\n';
ans=min(scc.dfs(scc.boss[i]),ans);
}
assert(ans<=k);
cout<<ans-1<<'\n';
}
