#include<bits/stdc++.h>
using namespace std;
const int N = 2e5;
const int inf = 2e9;
vector <int> e[N];
int v[N];
int sub[N];
vector <int> pos[N];
bool bad[N];
bool tree[N];
bool vis[N];
bool vis2[N];
int ans = inf;
int pr[N];
void cendecomp(int node){
int sz = 0;
int cen = -1,mn = inf;
auto dfs = [&](auto self, int node, int p) -> void{
for(auto i:e[node]){
if(i == p || bad[i])continue;
self(self, i, node);
}
sz++;
};
auto dfs2 = [&](auto self, int node, int p) -> void{
int mx = -1;
sub[node] = 1;
for(auto i:e[node]){
if(i == p || bad[i])continue;
self(self, i, node);
sub[node]+=sub[i];
mx = max(mx,sub[i]);
}
mx = max(mx,sz - sub[node]);
if(mx < mn){
mn = mx;
cen = node;
}
};
auto dfs3 = [&](auto self, int node, int p) -> void{
vis[node] = 0;
tree[node] = 0;
vis2[v[node]] = 0;
for(auto i:e[node]){
if(i == p || bad[i])continue;
self(self, i, node);
}
};
auto dfs4 = [&](auto self, int node, int p) -> void{
pr[node] = p;
tree[node] = 1;
for(auto i:e[node]){
if(i == p || bad[i])continue;
self(self, i, node);
}
};
dfs(dfs, node, -1);
dfs2(dfs2, node, -1);
dfs4(dfs4, cen, -1);
queue <int> q;
q.push(cen);
vis[cen] = 1;
bool ok = 1;
int nr = 0;
while(!q.empty()){
int x = q.front();
//cout<<"investigate:"<<x<<'\n';
q.pop();
if(!vis2[v[x]]){
vis2[v[x]] = 1;
nr++;
for(auto i:pos[v[x]]){
if(!tree[i]){
ok = 0;
break;
}
if(tree[i] && !vis[i]){
vis[i] = 1;
q.push(i);
}
}
if(!ok)break;
}
if(pr[x] != -1 && !vis[pr[x]]){
vis[pr[x]] = 1;
q.push(pr[x]);
}
}
if(ok){
ans = min(ans,nr);
}
dfs3(dfs3, cen, -1);
//cout<<cen<<' '<<nr<<' '<<ok<<'\n';
bad[cen] = 1;
for(auto i:e[cen]){
if(!bad[i]){
cendecomp(i);
}
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n,k;
cin>>n>>k;
for(int i = 0;i < n - 1;i++){
int u,w;
cin>>u>>w;
u--;w--;
e[u].push_back(w);
e[w].push_back(u);
}
for(int i = 0;i < n;i++){
cin>>v[i];
v[i]--;
pos[v[i]].push_back(i);
}
cendecomp(0);
cout<<ans - 1<<'\n';
return 0;
}
