#include <bits/stdc++.h>
using namespace std;
#define bit(i, x) (x >> i & 1)
#define ll long long
#define sz(x) (int)x.size()
const int N = 2e5 + 5;
const int mod = 998244353;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll rnd(ll l, ll r) {
return uniform_int_distribution<ll>(l, r)(rng);
}
int n, k;
vector<int> G[N];
int c[N];
// HLD DECOMPOSITION
int sz[N], big[N], parr[N], h[N];
int in[N], top[N], a[N], cnt;
// DNC GRAPH
int st[4 * N], cnt2;
vector<int> G2[4 * N];
// SCC
int num[4 * N], low[4 * N], cnt3;
int col[4 * N], val[4 * N], ct;
vector<int> stk;
// ADDITIONAL
vector<int> b[N];
// DAG
vector<int> G3[4 * N];
int bad[4 * N];
bool mark[4 * N];
// RESULT
int res;
void predfs(int u = 1, int par = -1) {
sz[u] = 1, big[u] = 0, parr[u] = par;
for(int v : G[u]) if(v != par) {
h[v] = h[u] + 1;
predfs(v, u);
sz[u] += sz[v];
if(sz[big[u]] < sz[v]) big[u] = v;
}
}
void dfshld(int u = 1, int topp = 1) {
in[u] = ++cnt;
a[cnt] = c[u];
top[u] = topp;
if(big[u]) dfshld(big[u], topp);
for(int v : G[u]) if(v != parr[u] && v != big[u]) dfshld(v, v);
}
int lca(int x, int y) {
while(top[x] != top[y]) {
if(h[top[x]] < h[top[y]]) swap(x, y);
x = parr[top[x]];
}
if(h[x] < h[y]) swap(x, y);
return y;
}
void build(int id, int l, int r) {
st[id] = ++cnt2;
if(l == r) {
G2[st[id]].push_back(a[l]);
return;
}
int mid = (l + r) / 2;
build(id * 2, l, mid);
build(id * 2 + 1, mid + 1, r);
G2[st[id]].push_back(st[id * 2]);
G2[st[id]].push_back(st[id * 2 + 1]);
}
void addedge(int id, int l, int r, int u, int v, int x) {
if(l > v || r < u) return;
if(l >= u && r <= v) {
G2[x].push_back(st[id]);
return;
}
int mid = (l + r) / 2;
addedge(id * 2, l, mid, u, v, x);
addedge(id * 2 + 1, mid + 1, r, u, v, x);
}
void addedge2(int x, int p) {
assert(h[x] >= h[p]);
int u = c[x];
while(top[x] != top[p]) {
addedge(1, 1, n, in[top[x]], in[x], u);
x = parr[top[x]];
}
if(in[p] > in[x]) swap(x, p);
addedge(1, 1, n, in[p], in[x], u);
}
void dfs(int u) {
num[u] = low[u] = ++cnt3;
stk.push_back(u);
for(int v : G2[u]) if(!col[v]) {
if(num[v]) low[u] = min(low[u], num[v]);
else {
dfs(v);
low[u] = min(low[u], low[v]);
}
}
if(num[u] == low[u]) {
ct++;
while(1) {
int top = stk.back();
stk.pop_back();
col[top] = ct;
val[ct] += (top <= k);
if(top == u) break;
}
}
}
void dag(int u) {
if(mark[u]) return;
mark[u] = 1;
for(int v : G3[u]) {
dag(v);
bad[u] |= bad[v];
}
}
signed main(int argc, char* argv[]) {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> k;
for(int i = 1; i < n; i++) {
int x, y; cin >> x >> y;
G[x].push_back(y);
G[y].push_back(x);
}
for(int i = 1; i <= n; i++) cin >> c[i];
predfs();
dfshld();
cnt2 = k;
build(1, 1, n);
for(int i = 1; i <= n; i++) b[c[i]].push_back(i);
for(int i = 1; i <= k; i++) if(!b[i].empty()) {
int u = b[i].front();
for(int j : b[i]) u = lca(u, j);
for(int j : b[i]) addedge2(j, u);
}
for(int i = 1; i <= cnt2; i++) if(!num[i]) dfs(i);
for(int i = 1; i <= cnt2; i++) {
for(int j : G2[i]) if(col[i] != col[j]) {
G3[col[i]].push_back(col[j]);
bad[col[i]] |= (val[col[j]] > 0);
}
}
res = k - 1;
for(int i = 1; i <= ct; i++) {
dag(i);
if(!bad[i] && val[i]) res = min(res, val[i] - 1);
}
cout << res;
// for(int i = 1; i <= n; i++) cout << i << " " << in[i] << "\n";
// for(int i = 1; i <= n; i++) cout << i << " " << big[i] << "\n";
// for(int i = 1; i <= n; i++) {
// for(int j = i; j <= n; j++) {
// cout << i << " " << j << " " << lca(i, j) << "\n";
// }
// }
return 0 ^ 0;
}
