#include <bits/stdc++.h>
using namespace std;
#define pb push_back
const int mxN = (int)2e5+2;
int n, m, ans = mxN;
vector<int> adj[mxN], v[mxN];
int C[mxN], sub[mxN], p[mxN], vis[mxN], vis2[mxN];
int getSub(int s, int par){
sub[s] = 1; p[s]=par;
for(auto u : adj[s])
if(u!=par and !vis[u])
sub[s]+=getSub(u,s);
return sub[s];
}
int findCen(int s, int p, int n){
for(auto u : adj[s])
if(u!=p and !vis[u] and sub[u]>n/2)
return findCen(u,s,n);
return s;
}
void dfs(int s, int par, bool ok){
p[s] = ok?par:-1;
if(ok) vis2[C[s]]=0;
for(auto u : adj[s])
if(u!=par and !vis[u]) dfs(u,s,ok);
}
void cenDec(int cen, int par){
cen = findCen(cen,par,getSub(cen,cen));
dfs(cen,cen,1); vis[cen]=vis2[C[cen]]=1;
queue<int> Q = queue<int>();
bool ok = 1; int cnt = 0;
for(auto u : v[C[cen]]){
if(ok and p[u]>=0) Q.push(u);
else ok=0;
}
while(!Q.empty() and ok){
auto a = Q.front(); Q.pop();
int CP = C[p[a]];
if(!vis2[CP]){
for(auto u : v[CP]){
if(ok and p[u]>=0) Q.push(u);
else ok=0;
}
if(ok) vis2[CP]=1; cnt++;
}
}
if(ok) ans = min(ans, cnt);
dfs(cen,cen,0);
for(auto u : adj[cen])
if(u!=par and !vis[u]) cenDec(u,cen);
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n >> m;
for(int i = 1; i < n; i++){
int a, b; cin >> a >> b;
adj[a].pb(b), adj[b].pb(a);
}
for(int i = 1; i <= n; i++)
cin >> C[i], v[C[i]].pb(i);
cenDec(1,-1); cout << ans << "\n";
}
