#include<bits/stdc++.h>
using namespace std;
bool M1;
#define PI 3.14159265358979323846
#define sz(a) (int)a.size()
#define all(x) x.begin(),x.end()
#define ii pair<int,int>
#define iii pair<int,ii>
#define iv pair<ii,ii>
#define se second
#define fi first
#define ffi fi.fi
#define sfi se.fi
#define sse se.se
#define fse fi.se
#define lt(i, c, d) for(int i = c; i <= d; ++i)
#define fl(i, c, d) for(int i = d; i >= c; --i)
#define pb push_back
#define emb emplace_back
#define emf emplace_front
#define em emplace
#define look_memory cerr<<abs(&M2-&M1)/1024.0/1024<<'\n'
#define look_time cerr << "TIME : " << clock() * 0.001 << "s" <<'\n'
const int N=1e6+5,lg=30,mod=1e9+7;
mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
int Rand(int u,int v){
return u+rd()%(v-u+1);
}
int dx[]={1,0,-1,0,1,1,-1,-1};
int dy[]={0,-1,0,1,1,-1,1,-1};
int node,k,C[N],ans=1e9,query,edge,up[N][lg+5],h[N],tin[N],tout[N],timer,ma[N];
vector<int>ver[N],mau[N];
struct HLD {
int n, curpos, curc;
vector<int> st, lazy, sl, h, up, curhead, curid, pos, posend, arr;
vector<vector<int>> edge;
HLD() : curpos(0), curc(0) {};
HLD(int _n) : n(_n), st(n * 4 + 5, 0), lazy(n * 4 + 5, 0), sl(n + 5), h(n + 5), up(n + 5),
curhead(n + 5), curid(n + 5), pos(n + 5), posend(n+5), arr(n + 5), edge(n + 5) {
curpos = curc = 0;
};
void addedge(int u, int v) {
edge[u].emplace_back(v);
edge[v].emplace_back(u);
}
void buildi(int id, int l, int r){
if (r==l) {
ver[id+k].emb(C[arr[l]]);
// cerr<<id+k<<" "<<C[arr[l]]<<'\n';
return;
}
int mid = (l + r) >> 1;
buildi(id << 1, l, mid);
buildi(id << 1 | 1, mid + 1,r);
ver[id+k].emb((id<<1|1)+k);
ver[id+k].emb((id<<1)+k);
// cerr<<id+k<<" "<<(id<<1|1)+k<<" "<<(id<<1)+k<<'\n';
// cerr<<(id<<1+k)
}
void update(int id, int l, int r, int u,int v, int val) {
if(r<u||l>v)return;
if (u<=l&&r<=v) {
ver[val].emb(id+k);
// cerr<<val<<" "<<id+k<<'\n';
return;
}
int mid = (l + r) >> 1;
update(id << 1, l, mid, u,v, val);
update(id << 1 | 1, mid + 1, r, u,v, val);
}
void dfs(int u, int cha) {
sl[u] = 1;
for (int v : edge[u]) {
if (v == cha) continue;
h[v] = h[u] + 1;
up[v] = u;
dfs(v, u);
sl[u] += sl[v];
}
}
void hld(int u, int cha) {
if (!curhead[curc]) curhead[curc] = u;
curid[u] = curc;
pos[u] = ++curpos;
arr[curpos] = u;
int nxt = 0;
for (int v : edge[u]) {
if (v != cha && sl[v] > sl[nxt]) nxt = v;
}
if (nxt) hld(nxt, u);
for (int v : edge[u]) {
if (v != cha && v != nxt) {
++curc;
hld(v, u);
}
}
posend[u]=curpos;
}
void build(int goc){
dfs(goc,-1);
hld(goc,-1);
buildi(1,1,n);
}
int lca(int u, int v) {
int id=C[v];
for(;curid[u]!=curid[v];v=up[curhead[curid[v]]]){
if(h[curhead[curid[u]]]>h[curhead[curid[v]]])swap(u,v);
update(1,1,n,pos[curhead[curid[v]]],pos[v],id);
}
if(h[u]>h[v])swap(u,v);
update(1,1,n,pos[u],pos[v],id);
return h[u] < h[v] ? u : v;
}
};
int low[N],tt[N],num[N],vis[N];
stack<int>st;
void tarjan(int u){
low[u]=num[u]=timer++;
vis[u]=1;tt[u]=1;
st.em(u);
// cerr<<u<<" ";
for(auto v:ver[u]){
if(!vis[v])
tarjan(v);
if(vis[v]==1)
low[u]=min(low[u],low[v]);
tt[u]&=tt[v];
}
if(low[u]==num[u]){
int v=-1,cnt=0;
bool lf=tt[u];
while(vis[u]==1){
v=st.top();
vis[v]=2;
tt[v]=0;
st.pop();
// cerr <<v<<" ";
cnt+=(v<=k);
}
// cerr<<'\n';
if(lf)
ans=min(ans,cnt-1);
}
}
bool M2;
void solve(){
cin >> node >> k;
HLD hld(node);
for(int i=1;i<node;++i){
int u,v;
cin >> u >> v;
hld.addedge(u,v);
}
for(int i=1;i<=node;++i){
cin >> C[i];
}
hld.build(1);
for(int i=1;i<=node;++i){
if(!ma[C[i]]){
ma[C[i]]=i;
}
else ma[C[i]]=hld.lca(ma[C[i]],i);
}
for(int i=1;i<=k;++i)if(!vis[i])tarjan(i);
cout << ans;
}
main()
{
srand(time(0));
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
#define task "aws"
if(fopen(task".inp","r")){
freopen(task".inp","r",stdin);
freopen(task".out","w",stdout);
}
int t=1;
// cin >> t;
while(t--){
solve();cout<<'\n';
}
look_memory;
look_time;
}
