#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = (int) 2e5 + 7;
const int INF = (int) 1e9;
int c[N], timestamp[N], added[N], p[N], subarb[N];
vector<int> g[N], colors[N];
bool visited[N];
void getsize(int u, int par = 0)
{
subarb[u] = 1;
for (auto it : g[u])
{
if (visited[it] == false && it != par)
{
getsize(it, u);
subarb[u] += subarb[it];
}
}
}
int getcentroid(int u, int total, int par = 0)
{
for (auto it : g[u])
{
if (visited[it] == false && it != par && subarb[it] > total / 2)
{
return getcentroid(it, total, u);
}
}
return u;
}
int Time = 0;
void dfs(int u, int par = 0)
{
p[u] = par;
timestamp[u] = Time;
for (auto it : g[u])
{
if (visited[it] == false && it != par)
{
dfs(it, u);
}
}
}
int ret = INF;
void solve(int u)
{
getsize(u);
int centroid = getcentroid(u, subarb[u], 0);
visited[centroid] = 1;
Time++;
timestamp[centroid] = Time;
for (auto it : g[centroid])
{
if (visited[it] == false)
{
dfs(it, centroid);
}
}
queue<int> q;
bool ok = 1;
q.push(c[centroid]);
added[c[centroid]] = Time;
int cnt = 1;
while (!q.empty())
{
int color = q.front();
q.pop();
for (auto it : colors[color])
{
if (timestamp[it] != Time)
{
ok = 0;
break;
}
if (it != centroid && added[c[p[it]]] != Time)
{
q.push(c[p[it]]);
added[c[p[it]]] = Time;
cnt++;
}
}
if (ok == 0)
{
break;
}
}
if (ok)
{
ret = min(ret, cnt - 1);
}
for (auto it : g[centroid])
{
if (visited[it] == false)
{
solve(it);
}
}
}
int main()
{
#ifdef ONPC
freopen("input.txt", "r", stdin);
#endif // ONPC
#ifndef ONPC
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#endif // ONPC
int n, k;
cin >> n >> k;
for (int i = 1; i < n; i++)
{
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
for (int i = 1; i <= n; i++)
{
cin >> c[i];
colors[c[i]].push_back(i);
}
solve(1);
cout << ret;
return 0;
}
