///In the name of GOD
//#pragma GCC optimize("O2")
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MXN = 4e5 + 10;
ll n, k, ans = 1e9;
ll A[MXN], sub[MXN], dad[MXN], Cnt[MXN], All[MXN];
vector<ll> adj[MXN], Ver[MXN], vec, col;
bool hide[MXN], bad[MXN], mark[MXN], vis[MXN];
void plant(ll u, ll par){
sub[u] = 1;
for(auto v : adj[u]){
if(v != par && !hide[v]){
plant(v, u), sub[u] += sub[v];
}
}
}
void Pre(ll u, ll par, ll dt){
dad[u] = par, mark[u] = 0;
if(dt == +1 && Cnt[A[u]] == 0) col.push_back(A[u]);
if(dt == +1) Cnt[A[u]] ++;
else Cnt[A[u]] = 0;
for(auto v : adj[u]){
if(v != par && !hide[v]) Pre(v, u, dt);
}
}
ll CRD(ll u, ll par, ll val){
for(auto v : adj[u]){
if(v == par || hide[v]) continue;
if(sub[v] >= val) return CRD(v, u, val);
}
return u;
}
void DMS(ll u, ll h){
plant(u, -1);
ll cent = CRD(u, -1, (sub[u] + 1) / 2);//attention
col.clear(), vec.clear();
Pre(cent, -1, +1);
for(auto c : col){
if(Cnt[c] != All[c]) bad[c] = 1;
else bad[c] = 0;
vis[c] = 0;
}
if(!bad[A[cent]]){
vec.push_back(cent);
ll tot = 0, pnt = 0; bool ok = 1;
while(pnt < vec.size()){
ll now = vec[pnt]; pnt ++;
if(mark[now] || now == -1) continue;
ll vr = now;
while(vr != -1 && !mark[vr]){
mark[vr] = 1;
if(!vis[A[vr]]){
tot ++; vis[A[vr]] = 1;
ok &= (!bad[A[vr]]);
if(!ok) break;
for(auto X : Ver[A[vr]]){
if(X == vr){
assert(mark[X]);
continue;
}
assert(!mark[X]);
vec.push_back(X);
}
}
if(!ok) break;
vr = dad[vr];
}
if(!ok) break;
}
for(auto c : col) vis[c] = 0;
if(ok) ans = min(ans, tot);
}
col.clear(), Pre(cent, -1, -1);
hide[cent] = 1;
for(auto v : adj[cent]){
if(!hide[v]) DMS(v, h + 1);
}
}
int main(){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
cin >> n >> k;
for(int i = 1; i < n; i ++){
ll u, v; cin >> u >> v;
adj[u].push_back(v), adj[v].push_back(u);
}
for(int i = 1; i <= n; i ++){
cin >> A[i], All[A[i]] ++;
Ver[A[i]].push_back(i);
}
DMS(1, 0);
cout << ans - 1 << '\n';
return 0;
}
/*!
HE'S AN INSTIGATOR,
ENEMY ELIMINATOR,
AND WHEN HE KNOCKS YOU BETTER
YOU BETTER LET HIM IN.
*/
//! N.N
