#include<bits/stdc++.h>
#define fr first
#define sc second
using namespace std;
void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
typedef long long ll;
#define USING_ORDERED_SET 0
#if USING_ORDERED_SET
#include<bits/extc++.h>
using namespace __gnu_pbds;
template<class T>using ordered_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
#endif
template<class T>void umax(T &a,T b){if(a<b)a=b;}
template<class T>void umin(T &a,T b){if(b<a)a=b;}
#ifdef IOI2021SG
#define printl(args...)printf(args)
#else
#define printl(args...)((void)0)
#endif
int n,k;
int tin[200005],tout[200005],timer,up[200005][18];
vector<int>g[200005],color[200005],g1[200005],g2[200005];
int a[200005];
void dfs(int v,int p){
tin[v]=++timer;
up[v][0]=p;
for(int i=1;i<18;i++)up[v][i]=up[up[v][i-1]][i-1];
for(int to:g[v])if(to!=p)dfs(to,v);
tout[v]=++timer;
}
bool upper(int a,int b){
return tin[a]<=tin[b]&&tout[a]>=tout[b];
}
int lca(int a,int b){
if(upper(a,b))return a;
if(upper(b,a))return b;
for(int i=17;i>=0;i--)if(!upper(up[a][i],b))a=up[a][i];
return up[a][0];
}
unordered_map<int,bool>vs[200005];
vector<pair<int,int>>edges;
void add_edge(int a,int b){
if(a^b){
if(vs[a][b])return;
vs[a][b]=true;
edges.emplace_back(a,b);
g1[a].push_back(b);
g2[b].push_back(a);
}
}
void add(int v,int a,int b){
int lca=::lca(a,b);
while(a!=lca){
a=up[a][0];
add_edge(v,::a[a]);
}
while(b!=lca){
b=up[b][0];
add_edge(v,::a[b]);
}
}
bool vis[200005];
vector<int>ordr,comp;
void dfs1(int v){
vis[v]=true;
for(int to:g1[v])if(!vis[to])dfs1(to);
ordr.push_back(v);
}
void dfs2(int v){
comp.push_back(v);
vis[v]=true;
for(int to:g2[v])if(!vis[to])dfs2(to);
}
int sz[200005];
int dp[200005];
int id[200005];
int go(int v){
if(~dp[v])return dp[v];
dp[v]+=sz[v]+1;
for(int to:g[v])dp[v]+=go(to);
return dp[v];
}
int main(){
memset(dp,-1,sizeof dp);
scanf("%d%d",&n,&k);
for(int i=1;i<n;i++){
int x,y;
scanf("%d%d",&x,&y);
g[x].push_back(y);
g[y].push_back(x);
}
for(int i=1;i<=n;i++){
scanf("%d",&a[i]);
color[a[i]].push_back(i);
}
dfs(1,1);
for(int i=1;i<=k;i++)
for(int j=1;j<color[i].size();j++)add(i,color[i][0],color[i][j]);
for(int i=1;i<=k;i++)if(!vis[i])dfs1(i);
memset(vis,0,sizeof vis);
timer=0;
for(int i=0;i<k;i++)if(!vis[ordr[k-i-1]]){
comp.clear();
dfs2(ordr[k-i-1]);
timer++;
sz[timer]=comp.size();
for(int to:comp)id[to]=timer;
}
for(int i=1;i<=timer;i++)g[i].clear(),vis[i]=0;
for(auto to:edges)
if(id[to.fr]!=id[to.sc])
g[id[to.fr]].push_back(id[to.sc]);
int ans=k;
for(int i=1;i<=timer;i++)umin(ans,go(i));
printf("%d",ans-1);
}
