#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <random>
#include <chrono>
#include <fstream>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int ans=LLONG_MAX/2;
vector<bool> del, visited;
vector<int> sz, got, cc, vect, full, par;
vector<vector<int> > graph, col;
void dfs_size(int node, int p){
sz[node]=1;
for (auto num:graph[node])if (num!=p&&!del[num])dfs_size(num, node), sz[node]+=sz[num];
}
int findcentroid(int node, int p, int size){
for (auto num:graph[node])if (num!=p&&!del[num]&&sz[num]>size/2)return findcentroid(num, node, size);
return node;
}
void dfs2(int node, int p, int c){
par[node]=p;
if (vect[node]==c)got.pb(node);
full.pb(node);
++cc[vect[node]];
for (auto num:graph[node])if (num!=p&&!del[num])dfs2(num, node, c);
}
void dfs(int node){
dfs_size(node, -1);
node=findcentroid(node, -1, sz[node]);
dfs2(node, -1, vect[node]);
del[node]=1;
if (col[vect[node]].size()==cc[vect[node]]){
int res=0;
visited[vect[node]]=1;
while (got.size()){
int c=par[got.back()];
got.pop_back();
if(c!=-1&&!visited[vect[c]]){
if (col[vect[c]].size()!=cc[vect[c]])goto end;
visited[vect[c]]=1;
for (auto a:col[vect[c]])got.pb(a);
++res;
}
}
ans=min(ans, res);
}
end:;
for (auto a:full)cc[vect[a]]=0, visited[a]=0;
full.clear();
got.clear();
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, k, a, b;
cin>>n>>k;
par.resize(n+1);
cc.resize(n+1, 0);
sz.resize(n+1);
del.resize(n+1, 0);
col.resize(k+1);
vect.resize(n+1);
graph.resize(n+1);
visited.resize(k+1, 0);
for (int i=1; i<n; ++i){
cin>>a>>b;
graph[a].pb(b);
graph[b].pb(a);
}
for (int i=1; i<=n; ++i)cin>>vect[i], col[vect[i]].pb(i);
dfs(1);
cout<<ans;
}
