#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "debug.h"
#else
#define debug(...) 0
#endif
typedef long long ll;
const int N = 2e3 + 4;
int n, k, c[N], cnt[N];
bool have[N], seen[N];
vector<int> T[N], D[N];
void dfs1(int v, int p) {
have[c[v]] = 1;
for (int u : T[v]) {
if (u != p) {
dfs1(u, v);
}
}
}
void dfs2(int v) {
seen[v] = 1;
for (int u : D[v]) {
if (seen[u] == 0) {
dfs2(u);
}
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> k;
for (int i = 1; i < n; i++) {
int v, u;
cin >> v >> u;
v--; u--;
T[v].push_back(u);
T[u].push_back(v);
}
for (int i = 0; i < n; i++) {
cin >> c[i];
c[i]--;
}
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
cnt[j] = have[j] = 0;
}
for (int v : T[i]) {
dfs1(v, i);
for (int j = 0; j < n; j++) {
cnt[j] += have[j];
have[j] = 0;
}
}
for (int j = 0; j < k; j++) {
if (cnt[j] >= 2) {
D[j].push_back(c[i]);
}
}
}
int ans = k;
for (int i = 0; i < k; i++) {
for (int j = 0; j < k; j++) {
seen[j] = 0;
}
dfs2(i);
int cand = 0;
for (int j = 0; j < k; j++) {
cand += seen[j];
}
ans = min(ans, cand);
}
cout << ans - 1;
return 0;
}
