#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int MAXN=2e5+6;
int n,k;
int c[MAXN];
vector<int>g[MAXN];
vector<int>nodes[MAXN];
bool cantuse[MAXN];
int ans;
bool used[MAXN];
bool used1[MAXN];
bool used2[MAXN];
int subtree[MAXN],par[MAXN];
void dfs(int u,int p)
{
par[u]=p;
subtree[u]=1;
for(auto xd:g[u])
{
if(xd==p)continue;
if(used[xd])continue;
dfs(xd,u);
subtree[u]+=subtree[xd];
}
}
int find_centroid(int u,int p,int n1)
{
for(auto xd:g[u])
{
if(xd==p)continue;
if(used[xd])continue;
if(subtree[xd]>n1/2)
{
return find_centroid(xd,u,n1);
}
}
return u;
}
void solve(int u)
{
dfs(u,0);
int cen=find_centroid(u,0,subtree[u]);
dfs(cen,0);
queue<int>q;
//cout<<"&& "<<u<<" "<<cen<<endl;
if(cantuse[c[cen]]==0)
{
for(auto xd:nodes[c[cen]])
{
q.push(xd);
}
int cnt=1;
vector<int>vc;
vc.push_back(c[cen]);
used2[c[cen]]=1;cantuse[c[cen]]=1;
bool imposibel=0;
while(!q.empty())
{
u=q.front();q.pop();
//cout<<u<<" ";
used1[u]=1;
if(par[u]==0)continue;
if(used1[par[u]]==0&&used2[c[par[u]]]==0&&cantuse[c[par[u]]])
{
imposibel=1;
break;
}
if(used2[c[par[u]]]==0)
{
//cout<<" *"<<c[par[u]]<<"* ";
used2[c[par[u]]]=1;vc.push_back(c[par[u]]);
cantuse[c[par[u]]]=1;
for(auto xd:nodes[c[par[u]]])
{
q.push(xd);
}
cnt++;
}
}
//cout<<endl;
//cout<<imposibel<<" "<<cnt<<endl;
if(!imposibel)ans=min(ans,cnt);
for(auto xd:vc)used2[xd]=0;
}
used[cen]=1;
for(auto xd:g[cen])
{
if(used[xd]==0)
{
solve(xd);
}
}
}
int main()
{
cin>>n>>k;
ans=k;
for(int i=1;i<n;i++)
{
int a,b;
cin>>a>>b;
g[a].push_back(b);
g[b].push_back(a);
}
for(int i=1;i<=n;i++)
{
cin>>c[i];
nodes[c[i]].push_back(i);
}
solve(1);
cout<<ans-1<<endl;
return 0;
}
