#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
#define FOR(i, j, n) for (int i = j; i<= n; i++)
#define ROF(i, n, j) for (int i = n; i>= j; i--)
#define pb push_back
#define mp make_pair
#define S second
#define F first
#define IOS ios_base :: sync_with_stdio(0); cin.tie(0); cout.tie(0)
/*
#pragma GCC optimization("Ofast, unroll-loops")
#pragma GCC target("avx2")
#pragma GCC target("bmi")
#pragma GCC target("bmi2")
#pragma GCC target("lzcnt")
*/
const int mn = 2e5 + 5, mlg = 22, mn2 = 6e5 + 10;
vector<int> A[mn2], a[mn], A2[mn2];
vector<pii> a2[mn];
int h[mn], siz[mn], par[mn], nemd[mn], beg[mn], c[mn], lift[mn][mlg];
int root[mn], g[mn], Siz[mn];
int k[mn], num[mn2];
bool mark[mn], MARK[mn2], MARK2[mn2], flag[mn2];
vector<int> melat[mn2];
struct Seg_tree
{
struct Node
{
int lc = -1, rc = -1;
}tmp;
int n = 0;
vector<Node> node;
void init(int id, int L, int R)
{
if (L+1 == R)
{
A[id].pb(nemd[L]);
return;
}
n++;
node.pb(tmp);
node[id].lc = n;
A[id].pb(n);
n++;
node.pb(tmp);
node[id].rc = n;
A[id].pb(n);
int mid = (L+R)/2;
init(node[id].lc, L, mid);
init(node[id].rc, mid, R);
}
void add(int id, int L, int R, int l, int r, int u)
{
if (L == l and R == r)
{
A[u].pb(id);
return;
}
int mid = (L+R)/2;
if (l >= mid) add(node[id].rc, mid, R,l, r, u);
else if (r <= mid) add(node[id].lc, L, mid, l, r, u);
else
{
add(node[id].lc, L, mid, l, mid, u);
add(node[id].rc, mid, R, mid, r, u);
}
}
}seg;
void dfs(int u)
{
mark[u] =1;
siz[u] =1;
for(auto v: a[u])
{
if (mark[v])
{
par[u] = v;
lift[u][0] = v;
continue;
}
h[v] = h[u]+1;
dfs(v);
siz[u] += siz[v];
a2[u].pb(mp(siz[v], v));
}
}
void dfs2(int u)
{
int v;
for(auto p: a2[u])
{
v = p.S;
if (v == a2[u][0].S)
{
root[v] = root[u];
}
else root[v] = v;
dfs2(v);
}
}
vector<int> alaki;
void DFS(int u)
{
MARK[u] = 1;
for(auto v: A[u])
{
if (!MARK[v]) DFS(v);
}
alaki.pb(u);
}
int ind = 0;
void DFS2(int u)
{
num[u] = ind;
melat[ind].pb(u);
MARK2[u] = 1;
for(auto v: A2[u])
{
if (!MARK2[v]) DFS2(v);
}
return;
}
struct HLD
{
void init(int n)
{
FOR(i, 1, n)
{
if (a2[i].size() != 0) continue;
Siz[root[i]] = 0;
int u = i;
while (root[u] != u)
{
Siz[root[u]]++;
g[u] = Siz[root[u]];
nemd[Siz[root[u]]] = c[u];
u = par[u];
}
Siz[root[u]]++;
g[u] = Siz[root[u]];
nemd[Siz[root[u]]] = c[u];
seg.n++;
beg[u] = seg.n;
seg.node.pb(seg.tmp);
seg.init(seg.n, 1, Siz[u]+1);
}
}
void update(int u, int v, int x)
{
if (h[root[u]] <= h[v])
{
seg.add(beg[root[u]], 1, Siz[root[u]]+1, g[u], g[v]+1, x);
}
else
{
seg.add(beg[root[u]], 1, Siz[root[u]]+1, g[u], Siz[root[u]]+1, x);
update(par[root[u]], v, x);
}
return;
}
}hld;
int get_lca(int u, int v)
{
if (h[u] < h[v]) swap(u, v);
ROF(i, 20, 0)
{
if (h[lift[u][i]] >= h[v])
{
u = lift[u][i];
}
}
if (u == v) return u;
ROF(i, 20, 0)
{
if (lift[u][i] != lift[v][i])
{
u = lift[u][i];
v = lift[v][i];
}
}
return par[u];
}
signed main()
{
IOS;
int n, m, u, v;
cin >> n >> m;
FOR(i,1 , n-1)
{
cin >> u >> v;
a[u].pb(v);
a[v].pb(u);
}
FOR(i, 1, n)
{
cin >>c[i];
}
FOR(i, 0, m)
{
seg.n++;
seg.node.pb(seg.tmp);
}
h[1] = 1;
dfs(1);
FOR(j, 1, 20)
{
FOR(i, 1, n)
{
lift[i][j] = lift[lift[i][j-1]][j-1];
}
}
FOR(i,1 , n)
{
sort(a2[i].begin(), a2[i].end());
reverse(a2[i].begin(), a2[i].end());
}
root[1] = 1;
dfs2(1);
//return 0;
FOR(i, 1, n)
{
if (k[c[i]] == 0) k[c[i]] = i;
else k[c[i]] = get_lca(i, k[c[i]]);
}
hld.init(n);
FOR(i, 1, n)
{
hld.update(i, k[c[i]], c[i]);
}
//return 0;
int N = seg.n;
FOR(i, 1, N)
{
for(auto v: A[i])
{
A2[v].pb(i);
}
}
FOR(i, 1, N)
{
if (!MARK[i])
{
//cout << i << endl;
DFS(i);
}
}
reverse(alaki.begin(), alaki.end());
for(auto i: alaki)
{
if (!MARK2[i])
{
ind++;
DFS2(i);
}
}
FOR(i, 1, N)
{
for(auto v: A[i])
{
if (num[v] != num[i]) flag[num[i]] = 1;
}
}
int ans = N, ted =0;
FOR(i, 1, ind)
{
if (flag[i]) continue;
ted = 0;
for(auto v: melat[i])
{
if (v > m) continue;
ted++;
}
if (ted != 0) ans = min(ans, ted);
}
cout << ans-1;
return 0;
}
