#include<bits/stdc++.h>
using ll = long long;
using namespace std;
#define pll pair <ll,ll>
#define fi first
#define se second
#define MP make_pair
#define sz(a) (ll((a).size()))
#define BIT(mask,i) (((mask) >> (i))&1)
#define MASK(i) (1LL << (i))
const ll MAXN = 2e5+100;
vector <ll> g[MAXN];
ll in[MAXN],out[MAXN],timeDFS;
ll c[MAXN];
ll n,k;
vector <ll> color[MAXN];
namespace SCC{
vector <ll> edge[MAXN];
vector <ll> rev[MAXN];
bool in[MAXN];
void add(ll x,ll y){
// cout<<x<<' '<<y<<'\n';
edge[x].push_back(y);
rev[y].push_back(x);
}
void dfs(ll u,vector <ll> gg[],vector <ll> &comp){
in[u] = 1;
for (auto v:gg[u]){
if (!in[v]){
dfs(v,gg,comp);
}
}
comp.push_back(u);
}
ll solve(){
vector <ll> order;
for (ll i = 1;i <= k;i ++){
if (!in[i]){
dfs(i,edge,order);
}
}
memset(in,0,sizeof in);
reverse(order.begin(),order.end());
ll res = k;
for (auto x:order){
if (!in[x]){
vector <ll> comp;
dfs(x,rev,comp);
bool ok = 1;
for (auto x:comp){
for (auto y:edge[x]){
if (!in[y]){ok=0;}
}
}
if (ok && sz(comp) < res){
res = sz(comp);
}
}
}
return res;
}
}
void dfs(ll u,ll p){
in[u] = ++timeDFS;
color[c[u]].push_back(in[u]);
for (auto v:g[u]){
if (v==p)continue;
dfs(v,u);
}
out[u] = timeDFS;
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(nullptr);
cin>>n>>k;
for (ll i = 1;i < n;i ++){
ll u,v;
cin>>u>>v;
g[u].push_back(v);
g[v].push_back(u);
}
for (ll i = 1;i <= n;i ++)cin>>c[i];
dfs(1,1);
for (ll i = 1;i <= n;i ++){
for (auto v:g[i]){
if (c[v] != c[i]){
if (in[v] > in[i]){
auto tmp = lower_bound(color[c[i]].begin(),color[c[i]].end(),in[v]);
if (tmp!=color[c[i]].end() && (*tmp) <= out[v]){
SCC::add(c[i],c[v]);
}
}
else{
auto tmp = upper_bound(color[c[i]].begin(),color[c[i]].end(),out[i]) - lower_bound(color[c[i]].begin(),color[c[i]].end(),in[i]);
if (tmp != sz(color[c[i]]))SCC::add(c[i],c[v]);
}
}
}
}
cout<<SCC::solve()-1;
}
