#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define vi vector<int>
using namespace std;
const int N = 2e5 + 5;
int n, k;
int c[N];
int sz[N];
int vis[N];
int activeNode[N];
int activeColor[N];
int parentArr[N];
int ans = 1e18;
vector<int> adj[N];
vector<int> nodesOfColor[N];
vector<int> componentNodes;
vector<int> usedColors;
void getSize(int node, int parent){
sz[node] = 1;
for(auto child : adj[node]){
if(child == parent || vis[child]) continue;
getSize(child, node);
sz[node] += sz[child];
}
}
int getCentroid(int node, int parent, int total){
for(auto child : adj[node]){
if(child == parent || vis[child]) continue;
if(sz[child] > total / 2){
return getCentroid(child, node, total);
}
}
return node;
}
void dfsComponent(int node, int parent){
parentArr[node] = parent;
activeNode[node] = 1;
componentNodes.pb(node);
for(auto child : adj[node]){
if(child == parent || vis[child]) continue;
dfsComponent(child, node);
}
}
void decompose(int entry){
getSize(entry, -1);
int centroid =
getCentroid(entry, -1, sz[entry]);
componentNodes.clear();
dfsComponent(centroid, -1);
queue<int> q;
q.push(centroid);
vector<int> colorUsed(k, 0);
vector<int> nodeUsed;
vector<int> colorList;
int cntColors = 0;
bool ok = true;
activeColor[c[centroid]] = 1;
colorList.pb(c[centroid]);
cntColors++;
while(!q.empty()){
int node = q.front();
q.pop();
if(!activeNode[node]){
ok = false;
break;
}
if(!colorUsed[c[node]]){
colorUsed[c[node]] = 1;
for(auto u : nodesOfColor[c[node]]){
if(!activeNode[u]){
ok = false;
break;
}
q.push(u);
}
if(!ok) break;
cntColors++;
}
int cur = node;
while(cur != -1){
if(activeNode[cur]){
q.push(cur);
}
cur = parentArr[cur];
}
}
if(ok){
ans = min(ans, cntColors - 1);
}
for(auto u : componentNodes){
activeNode[u] = 0;
}
vis[centroid] = 1;
for(auto child : adj[centroid]){
if(!vis[child]){
decompose(child);
}
}
}
signed main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> k;
for(int i = 1; i < n; i++){
int u, v;
cin >> u >> v;
u--;
v--;
adj[u].pb(v);
adj[v].pb(u);
}
for(int i = 0; i < n; i++){
cin >> c[i];
c[i]--;
nodesOfColor[c[i]].pb(i);
}
decompose(0);
cout << ans << '\n';
}
