#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define eb emplace_back
#define mt make_tuple
#define all(x) (x).begin(), (x).end()
#define sz(x) int(x.size())
#define MOD 1000000007
typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;
const ll INF=LLONG_MAX;
const int mxn=2e5+5;
bool DEBUG=0;
int n,k,city[mxn],siz[mxn],h[mxn],par[mxn],ans;
vi adj[mxn],adj2[mxn];
set<int>nodes,mcity,usedcity;
//required to vis, merged city, visited city
int citycnt[mxn];
bool vis[mxn];
struct DSU{
vi par;
DSU(int n){
for(int i=0; i<n; i++){
par.eb(i);
}
}
void reset(int n){
par.resize(n);
for(int i=0; i<n; i++){
par[i]=i;
}
}
void resetnode(int u){
par[u]=u;
}
int rt(int u){
if(u!=par[u])par[u]=rt(par[u]);
return par[u];
}
void merge(int u, int v){
u=rt(u); v=rt(v);
if(u==v)return;
if(h[u]>h[v])swap(u,v);
par[v]=u;
}
int getrt(int u){
return rt(u);
}
};
DSU dsu(1);
void dfs_sz(int u, int p=-1){
siz[u]=1;
citycnt[city[u]]++;
usedcity.insert(city[u]);
for(int v:adj[u]){
if(v==p||vis[v])continue;
dfs_sz(v,u);
siz[u]+=siz[v];
}
return;
}
int centroid(int u, int p, int sizz){
for(int v:adj[u]){
if(v==p||vis[v])continue;
if(siz[v]*2>sizz)return centroid(v,u,sizz);
}
return u;
}
void dfs(int u, int p){
nodes.insert(u);
for(int v:adj[u]){
if(v==p||vis[v])continue;
par[v]=u;
h[v]=h[u]+1;
dfs(v,u);
}
return;
}
void ctsolve(int ct){
//assuming capital city is centroid
par[ct]=-1;
h[ct]=0;
dfs(ct,-1);
int City = city[ct];
set<int>ncity;
//cities need to visit
ncity.emplace(City);
bool ok=1;
if(sz(adj2[City])!=citycnt[City]){
ok=0; ncity.erase(City);
}
while(ncity.size()&&ok){
int u = *ncity.begin();
ncity.erase(u);
mcity.insert(u);
for(int v:adj2[u]){
while(v!=ct){
v=dsu.rt(v);
if(v==ct)break;
if(ncity.find(city[par[v]])==ncity.end()&&mcity.find(city[par[v]])==mcity.end()){
if(sz(adj2[city[par[v]]])==citycnt[city[par[v]]])ncity.insert(city[par[v]]);
else{
ok=0;
break;
}
}
dsu.merge(par[v],v);
v=par[v];
}
if(!ok)break;
}
}
for(int x:nodes){
dsu.resetnode(x);
}
for(int x:usedcity)citycnt[x]=0;
if(ok)ans = min(ans,sz(mcity));
nodes=mcity=usedcity=set<int>();
return;
}
void solve(int u=0){
dfs_sz(u);
int ct = centroid(u,-1,siz[u]);
ctsolve(ct);
vis[ct]=1;
for(int v:adj[ct]){
if(!vis[v]){
solve(v);
}
}
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
//freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
cin >> n >> k;
ans=k;
dsu.reset(n);
for(int i=0; i<n-1; i++){
int u,v;
cin >> u >> v;
u--; v--;
adj[u].eb(v);
adj[v].eb(u);
}
for(int i=0; i<n; i++){
cin>>city[i];
city[i]--;
adj2[city[i]].eb(i);
}
for(int i=0; i<k; i++){
if(sz(adj2[i])==1){
cout << 0 << '\n';
return 0;
}
}
solve(0);
cout << ans-1 << '\n';
return 0;
}
// READ & UNDERSTAND
// ll, int overflow, array bounds, memset(0)
// special cases (n=1?), n+1 (1-index)
// do smth instead of nothing & stay organized
// WRITE STUFF DOWN
