#include<bits/stdc++.h>
#include<fstream>
#pragma GCC optimize("Ofast,O3,unroll-loops")
#pragma GCC target("avx2")
using namespace std;
//ifstream fin("FEEDING.INP");
//ofstream fout("FEEDING.OUT");
#define sz(a) (int)a.size()
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
const ll mod = 1e9 + 7;
const int mxn = 2e5 + 5, mxr = 25e3, sq = 500, mxv = 1e6 + 5, mxvv = 130, pr = 31, inf = 1e9;
int n, k;
int sz[mxn + 1];
vt<int>adj[mxn + 1], tocol[mxn + 1];
int pa[mxn + 1], a[mxn + 1], cnt[mxn + 1], ans = inf;
bool vis[mxn + 1], vis2[mxn + 1];
vt<int>comp;
int dfs(int s, int pre){
sz[s] = 1;
for(auto i: adj[s]){
if(i != pre && !vis[i]){
sz[s] += dfs(i, s);
}
}
return(sz[s]);
}
int centroid(int s, int pre, int need){
for(auto i: adj[s]){
if(i != pre && !vis[i]){
if(sz[i] * 2 > need)return(centroid(i, s, need));
}
}
return(s);
}
void go(int s, int pre){
pa[s] = pre; comp.pb(s);
for(auto i: adj[s]){
if(i != pre && !vis[i]){
go(i, s);
}
}
}
void solve(int s){
comp.clear();
int c = centroid(s, -1, dfs(s, -1));
go(c, -1);
vis[c] = 1;
for(auto i: comp){
tocol[a[i]].pb(i);
}
queue<int>q;
vis2[a[c]] = 1;
q.push(a[c]);
int need = 1; bool ok = 1;
while(!q.empty()){
int nw = q.front(); q.pop();
if(cnt[nw] != sz(tocol[nw])){
ok = 0; break;
}
for(auto i: tocol[nw]){
int to = pa[i];
if(to != -1){
if(!vis2[a[to]]){
vis2[a[to]] = 1; need++;
q.push(a[to]);
}
}
}
}
for(auto i: comp){
tocol[a[i]].clear(); vis2[a[i]] = 0;
}
if(ok)ans = min(ans, need - 1);
for(auto i: adj[c]){
if(!vis[i]){
solve(i);
}
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> k;
for(int i = 1; i < n; i++){
int u, v; cin >> u >> v;
adj[u].pb(v); adj[v].pb(u);
}
for(int i = 1; i <= n; i++){
cin >> a[i]; cnt[a[i]]++;
}
solve(1);
cout << ans;
return(0);
}
