#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define ar array
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int maxn = 2e5 + 5, inf = 1e9;
int N, K;
vector<int> same[maxn], adj[maxn];
int sz[maxn], del[maxn], vis[maxn], cvis[maxn], col[maxn], par[maxn];
vector<int> vec;
int ret = inf, num[maxn];
void prepare(int u, int p)
{
vec.pb(col[u]);
par[u] = p;
same[col[u]].pb(u);
vis[u] = cvis[col[u]] = 0;
for(int v : adj[u]) if(v != p && !del[v]){
prepare(v, u);
}
}
void findsz(int u, int p)
{
sz[u] = 1;
for(int v : adj[u]) if(v != p && !del[v]){
findsz(v, u);
sz[u] += sz[v];
}
}
int findcen(int u, int p, int siz)
{
for(int v : adj[u]) if(v != p && !del[v]){
if(sz[v] > siz / 2) return findcen(v, u, siz);
}
return u;
}
void decomp(int u)
{
findsz(u, u);
u = findcen(u, u, sz[u]);
prepare(u, u);
del[u] = true;
queue<int> q;
q.push(col[u]);
cvis[col[u]] = true;
int cnt = 0;
while(q.size()){
int c = q.front(); q.pop();
++cnt;
for(int v : same[c]){
while(!vis[v]){
vis[v] = true;
if(!cvis[col[v]]){
cvis[col[v]] = true;
q.push(col[v]);
}
v = par[v];
}
}
}
bool flag = true;
for(int c : vec){
if(cvis[c] && num[c] != same[c].size())
flag = false;
}
//cerr << u << ' ' << cnt << '\n';
if(flag)
ret = min(ret, cnt - 1);
for(int c : vec)
same[c].clear();
vec.clear();
for(int v : adj[u])
if(!del[v])
decomp(v);
}
signed main(void)
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifdef LOCAL
freopen("A.INP", "r", stdin);
freopen("A.OUT", "w", stdout);
#endif // LOCAL
cin >> N >> K;
for(int i = 1; i < N; ++i){
int u, v; cin >> u >> v;
adj[u].eb(v); adj[v].eb(u);
}
for(int i = 1; i <= N; ++i){
cin >> col[i];
++num[col[i]];
}
decomp(1);
cout << ret;
}
