#include <bits/stdc++.h>
#define pb push_back
using namespace std;
const int N = 2e5 + 10, INF = 1e9;
bool mark[N], flag[N];
int n, k, C[N], ans = INF, ptr, p[N];
vector<int> G[N], vec[N];
queue<int> q;
void dfs1(int v) {
ptr++;
for (auto e : vec[v])
if (!mark[e]) q.push(e);
flag[v] = true;
}
void dfs2(int v, int par) {
p[v] = par;
for (auto e : G[v])
if (e ^ par) dfs2(e, v);
}
void f(int v) {
if (!mark[v]) {
if (!flag[C[v]]) dfs1(C[v]);
f(p[v]);
}
}
int main() {
ios:: sync_with_stdio(0), cin.tie(0);
cin >> n >> k;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
G[u].pb(v);
G[v].pb(u);
}
for (int i = 1; i <= n; i++) {
int c;
cin >> c;
C[i] = c;
vec[c].pb(i);
}
ans = k;
for (int i = 1; i <= k; i++) {
if (vec[i].size()) {
mark[*vec[i].begin()] = true;
ptr = 0, dfs1(i);
dfs2(*vec[i].begin(), 0);
while (!q.empty()) {
auto u = q.front();
q.pop(), f(u);
}
ans = min(ans, ptr);
for (int j = 1; j <= n; j++) flag[j] = false;
for (int j = 1; j <= n; j++) mark[j] = false;
}
}
cout << ans - 1 << endl;
}
