#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<ll, ll>
#define f first
#define s second
#define SZ(x) (int)((x).size())
#define ALL(x) (x).begin(), (x).end()
#define pb push_back
#define MX(a,b) a = max(a,b)
#define MN(a,b) a = min(a,b)
#define FOR(i,a,b) for (int i = a; i<b; ++i)
#define REP(i,n) for (int i = 0; i<n; ++i)
#define REP1(i,n) for (int i = 1; i<=n; ++i)
#ifdef BALBIT
#define bug(...) cerr<<"#"<<__LINE__<<"- "<<#__VA_ARGS__<<": ", _do(__VA_ARGS__)
template<typename T> void _do(T && x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T && x, S && ...y){cerr<<x<<", "; _do(y...);}
#else
#define bug(...)
#define endl '\n'
#endif // BALBIT
const int maxn = 2e5+5;
const int mod = 1e9+7;
bool dead[maxn];
bool colorok[maxn];
int color[maxn];
int sz[maxn];
vector<int> g[maxn];
vector<int> where[maxn]; // where are the nodes of this color?
void predfs(int v, int p) {
sz[v] = 1;
for (int u : g[v]) {
if (dead[u]) continue;
if (u != p) {
predfs(u,v);
sz[v] += sz[u];
}
}
}
int allsz = -1;
int getcen(int v, int p) {
for (int u : g[v]) {
if (dead[u]) continue;
if (u != p && sz[u] > (allsz)/2) {
return getcen(u,v);
}
}
return v;
}
int dep[maxn];
bool done[maxn]; // make sure to clear!!!
bool inque[maxn]; // make sure to clear!!!
int par[maxn];
vector<int> colorshere;
int subtree[maxn]; // which subtree is it?????
void dfs(int v, int p) {
done[v] = 0; inque[color[v]] = 0;
colorshere.pb(color[v]);
for (int u : g[v]) {
if (dead[u]) continue;
if (u!=p) {
dep[u] = dep[v] + 1; par[u] = v;
if (p == -1) {
subtree[u] = u;
}else{
subtree[u] = subtree[v];
}
dfs(u,v);
}
}
}
int re = maxn;
void decomp(int stv, int lay) {
predfs(stv, -1); allsz = sz[stv];
int cen = getcen(stv, -1);
bug(stv, lay, cen);
stv = -1;
dep[cen] = 0;
colorshere.clear();
dfs(cen, -1);
sort(ALL(colorshere)); colorshere.resize(unique(ALL(colorshere)) - colorshere.begin());
done[cen] = 1;
if (colorok[color[cen]]) {
queue<int> q; q.push(color[cen]);
inque[color[cen]] = 1;
int nmerge = 0;
bool bad = 0;
while (!q.empty()) {
int cc = q.front(); q.pop();
for (int x : where[cc]) {
for (int at = x; !done[at]; at= par[at]) {
done[at] = 1;
int c = color[at];
if (!inque[c] && colorok[c]) {
inque[c] = 1; q.push(c); ++nmerge;
}
if (!colorok[c]) {
bad = 1; break;
}
}
if (bad) break;
}
}
if (!bad) {
bug(nmerge);
MN(re, nmerge);
}
}
dead[cen] = 1; colorok[color[cen]] = 0;
for (int t : colorshere) {
if (colorok[t]) {
int mn = maxn, mx = -1;
for (int x : where[t]) {
MN(mn, subtree[x]); MX(mx, subtree[x]);
}
if (mn < mx) {
colorok[t] = 0;
}
}
}
for (int u : g[cen]) {
if (!dead[u]) {
decomp(u, lay+1);
}
}
}
signed main(){
ios::sync_with_stdio(0), cin.tie(0);
bug(1,2);
int n,c; cin>>n>>c;
REP(i,n-1) {
int a,b; cin>>a>>b; --a; --b;
g[a].pb(b); g[b].pb(a);
}
REP(i,n) {
cin>>color[i]; colorok[color[i]] = 1;
where[color[i]].pb(i);
}
decomp(0, 0);
cout<<re<<endl;
}
