# include <iostream>
# include <vector>
# include <queue>
using namespace std;
const int MAX=2e5+11,INF=1e9;
int n,k;
vector<int> adj[MAX];
vector<int> colors[MAX];
int col[MAX];
bool killed[MAX];
int sz[MAX];
void dfs_sz(int curr, int par)
{
sz[curr]=1;
for(int nxt: adj[curr])
{
if(nxt==par or killed[nxt]) continue;
dfs_sz(nxt,curr);
sz[curr]+=sz[nxt];
}
}
int get_centroid(int curr, int par, int N)
{
for(int nxt: adj[curr])
{
if(nxt==par or killed[nxt]) continue;
if(sz[nxt]*2>N) return get_centroid(nxt,curr,N);
}
return curr;
}
bool state[MAX];
void dfs_state(int curr, int par)
{
state[curr]^=1;
for(int nxt: adj[curr])
{
if(nxt==par or killed[nxt]) continue;
dfs_state(nxt,curr);
}
}
bool vis[MAX];
bool vis_col[MAX];
int h[MAX];
int up[MAX];
void dfs_init(int curr, int par)
{
for(int nxt: adj[curr])
{
if(nxt==par or killed[nxt]) continue;
h[nxt]=h[curr]+1;
up[nxt]=curr;
dfs_init(nxt,curr);
}
}
int solve(int start)
{
h[start]=0;
dfs_init(start,0);
queue<int> q;
for(int x: colors[col[start]])
{
if(!state[x])
{
vis[start]=0;
vis_col[col[start]]=0;
return INF;
}
if(x!=start) q.push(x);
else
{
vis[start]=1;
vis_col[col[start]]=1;
}
}
bool f=1;
int ans=1;
vector<int> toRem;
while(q.size()>0)
{
int curr=q.front();
q.pop();
while(!vis[curr])
{
toRem.push_back(curr);
vis[curr]=1;
if(vis_col[col[curr]]==0)
{
ans++;
vis_col[col[curr]]=1;
for(int nxt: colors[col[curr]])
{
if(!state[nxt])
{
f=0;
break;
}
q.push(nxt);
}
}
curr=up[curr];
}
if(!f) break;
}
toRem.push_back(start);
for(int x: toRem)
{
vis[x]=0;
vis_col[col[x]]=0;
}
if(f) return ans;
else return INF;
}
int ANS=INF;
void cd(int curr)
{
dfs_sz(curr,0);
curr=get_centroid(curr,0,sz[curr]);
dfs_state(curr,0);
ANS=min(ANS,solve(curr));
dfs_state(curr,0);
killed[curr]=1;
for(int nxt: adj[curr])
{
if(!killed[nxt]) cd(nxt);
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>k;
for(int i=1;i<n;i++)
{
int u,v;
cin>>u>>v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for(int i=1;i<=n;i++)
{
cin>>col[i];
colors[col[i]].push_back(i);
}
cd(1);
cout<<ANS-1<<"\n";
return 0;
}
