#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define ll long long
#define ii pair<ll, ll>
#define fi first
#define se second
const long mxN = 2e5 + 7;
int n, in[mxN], h[mxN], par[mxN][30], mn[mxN], k, num, c[mxN], ans, lst[mxN], root[mxN];
vector<int> w[mxN], ww[mxN];
void TiTo(int j)
{
in[j] = ++num;
h[j] = h[par[j][0]] + 1;
for (int i = 1; i <= 20; i++)
par[j][i] = par[par[j][i - 1]][i - 1];
for (int i : w[j])
{
if (in[i])
continue;
par[i][0] = j;
TiTo(i);
}
}
bool cmp(int u, int v)
{
return in[u] < in[v];
}
int LCA(int u, int v)
{
if (h[u] < h[v])
swap(u, v);
for (int i = 20; i >= 0; i--)
{
if (h[par[u][i]] >= h[v])
u = par[u][i];
}
if (u == v)
return h[u];
for (int i = 20; i >= 0; i--)
{
if (par[u][i] != par[v][i])
{
u = par[u][i];
v = par[v][i];
}
}
return h[u] - 1;
}
void DFS(int j)
{
root[j] = j;
while (h[root[j]] > h[mn[c[j]]])
{
root[j] = par[root[j]][0];
ww[c[j]].push_back(c[root[j]]);
root[j] = root[root[j]];
}
for (int i : w[j])
{
if (h[i] < h[j])
continue;
DFS(i);
}
}
int cs[mxN], low[mxN], vis[mxN], block, ltm[mxN];
vector<int> vc;
void Tarzan(int j)
{
cs[j] = low[j] = ++num;
vis[j] = 1;
vc.push_back(j);
for (int i : ww[j])
{
if (!vis[i])
Tarzan(i);
if (vis[i] == 1)
low[j] = min(low[i], low[j]);
}
if (low[j] != cs[j])
return;
bool tt = 0;
int cntt = 0;
block++;
while (vis[j] == 1)
{
int i = vc.back();
vc.pop_back();
vis[i] = 2;
ltm[i] = block;
cntt++;
for (int u : ww[i])
tt |= (ltm[u] && ltm[u] != block);
}
if (!tt)
ans = min(ans, cntt - 1);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
cin >> n >> k;
for (int i = 1; i < n; i++)
{
int u, v;
cin >> u >> v;
w[u].push_back(v);
w[v].push_back(u);
}
TiTo(1);
for (int i = 1; i <= n; i++)
{
cin >> c[i];
if (mn[c[i]])
mn[c[i]] = LCA(mn[c[i]], i);
else
mn[c[i]] = i;
}
DFS(1);
ans = n;
for (int i = 1; i <= k; i++)
{
if (!vis[i])
Tarzan(i);
}
cout << ans;
}
