#include <bits/stdc++.h>
#define ll long long
#define s second
#define f first
#define pb push_back
#define pii pair <int,int>
#define left (h<<1),l,(l + r)/2
#define right ((h<<1)|1),(l + r)/2 + 1,r
// #define int ll
using namespace std;
const int N = 2e5 + 3;
int color[N],vis[N],centroid,f[N];
int tot[N],cnt[N],ans,parent[N];
vector <int> v[N],vec[N];
int dfs(int x,int par,int n,int dl){
// cout<<x<<" & "<<color[x]<<endl;
cnt[color[x]] += dl;
int s = 1;
for (int to: v[x]){
if (to == par || vis[to]) continue;
s += dfs(to,x,n,dl);
}
if (centroid == -1 && (par == -1 || s*2 >= n))
centroid = x;
return s;
}
void DFS(int x,int par){
parent[x] = par;
for (int to: v[x]){
if(to==par || vis[to]) continue;
DFS(to,x);
}
}
void go(int x,int n,int dep){
centroid = -1;
dfs(x,-1,n,1);
DFS(centroid,-1);
queue <int> q;
vector <int> rl;
q.push(color[centroid]);
rl.pb(color[centroid]);
f[color[centroid]] = 1;
int check = 1,add = 0;
while (q.size()){
int c = q.front(); q.pop();
add++;
if (tot[c] != cnt[c]) {check = 0; break;}
for (int x: vec[c]){
int p = parent[x];
if (p != -1 && color[p] != color[x] && !f[color[p]]){
f[color[p]] = 1;
rl.pb(color[p]);
q.push(color[p]);
}
}
}
for (int x: rl)
f[x] = 0;
if (check) ans=min(ans,add - 1);
dfs(x,-1,n,-1);
vis[centroid] = 1;
for (int to: v[centroid]){
if(!vis[to]) go(to,n/2,dep + 1);
}
}
signed main(){
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n,k;
cin>>n>>k;
for (int i = 1; i < n; i++){
int a,b;
cin>>a>>b;
v[a].pb(b);
v[b].pb(a);
}
for (int i = 1; i <= n; i++){
cin >> color[i];
tot[color[i]]++;
vec[color[i]].pb(i);
}
ans = n;
go(1,n,1);
cout<<ans<<endl;
}
