#include <bits/stdc++.h>
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
using namespace std;
const int N = 2e5 + 5;
vector<int> g[N];
int n, K;
int c[N];
vector<int> city[N];
int in[N], tour[N], sz[N], time_dfs, fa[N];
void pre_dfs(int u) {
sz[u] = 1;
for(int v : g[u]) if(v != fa[u]) {
fa[v] = u;
pre_dfs(v);
sz[u] += sz[v];
}
}
int chainId[N], chainRoot[N], curChain;
void hld(int u) {
if(!chainId[u]) {
chainId[u] = ++curChain;
chainRoot[curChain] = u;
}
in[u] = ++time_dfs;
tour[time_dfs] = u;
int hc = -1;
for(int v : g[u]) if(v != fa[u]) {
if(hc == -1 || sz[v] > sz[hc]) hc = v;
}
if(hc != -1) {
chainId[hc] = chainId[u];
hld(hc);
}
for(int v : g[u]) if(v != fa[u] && v != hc) {
hld(v);
}
}
vector<int> adj[5 * N];
int num;
int it[N << 2];
void build(int k, int l, int r) {
it[k] = ++num;
if(l == r) {
// cout << it[k] << ' ' << c[tour[l]] << '\n';
adj[it[k]].emplace_back(c[tour[l]]);
return;
}
int mid = l + r >> 1;
build(k << 1, l, mid);
build(k << 1 | 1, mid + 1, r);
adj[it[k]].emplace_back(it[k << 1]);
adj[it[k]].emplace_back(it[k << 1 | 1]);
}
void update(int k, int l, int r, int u, int v, int par) {
if(u <= l && r <= v) {
// cout << par << ' ' << it[k] << '\n';
adj[par].emplace_back(it[k]);
return;
}
int mid = l + r >> 1;
if(mid >= u) update(k << 1, l, mid, u, v, par);
if(mid + 1 <= v) update(k << 1 | 1, mid + 1, r, u, v, par);
}
void add(int u, int v, int par) {
// cout << u << ' ' << v << ' ' << par << '\n';
while(chainId[u] != chainId[v]) {
if(chainId[u] > chainId[v]) {
update(1, 1, n, in[chainRoot[chainId[u]]], in[u], par);
u = fa[chainRoot[chainId[u]]];
} else {
update(1, 1, n, in[chainRoot[chainId[v]]], in[v], par);
v = fa[chainRoot[chainId[v]]];
}
}
if(in[u] < in[v]) update(1, 1, n, in[u], in[v], par);
else update(1, 1, n, in[v], in[u], par);
}
int dfn[5 * N], low[5 * N], id[5 * N], scc, tim, deg[5 * N];
int dp[5 * N];
stack<int> stk;
void tarjan(int u) {
dfn[u] = low[u] = ++tim;
stk.emplace(u);
for(int v : adj[u]) {
if(id[v]) continue;
if(!dfn[v]) {
tarjan(v);
low[u] = min(low[u], low[v]);
} else {
low[u] = min(low[u], dfn[v]);
}
}
if(low[u] == dfn[u]) {
for(++scc; true; ) {
int v = stk.top();
stk.pop();
id[v] = scc;
if(u == v) break;
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
file("A") else file("task");
cin >> n >> K;
for(int i = 1, u, v; i < n; ++i) {
cin >> u >> v;
g[u].emplace_back(v);
g[v].emplace_back(u);
}
for(int i = 1; i <= n; ++i) {
cin >> c[i];
city[c[i]].emplace_back(i);
}
pre_dfs(1);
hld(1);
num = K;
build(1, 1, n);
for(int i = 1; i <= K; ++i) {
for(int j = 0; j < (int)city[i].size() - 1; ++j) {
add(city[i][j], city[i][j + 1], i);
}
}
for(int i = 1; i <= num; ++i) if(!dfn[i]) tarjan(i);
for(int i = 1; i <= K; ++i) {
dp[id[i]]++;
}
for(int i = 1; i <= num; ++i) for(int j : adj[i]) {
if(id[i] != id[j]) {
++deg[id[i]];
}
}
int ans = K;
for(int i = 1; i <= scc; ++i) if(deg[i] == 0) {
ans = min(ans, dp[i] - 1);
}
cout << ans << '\n';
return 0;
}
