#include <bits/stdc++.h>
using namespace std;
void dfs(int x, int par, vector<vector<int>> &AR, vector<int> &depth, vector<int> &p, int prof)
{
depth[x] = prof;
p[x] = par;
for (int i = 0; i < AR[x].size(); i++)
{
if (AR[x][i] == par)
continue;
dfs(AR[x][i], x, AR, depth, p, prof + 1);
}
}
vector<int> lead;
int find(int x) { return (lead[x] == x) ? x : lead[x] = find(lead[x]); }
void dfs2(int x, int p, vector<vector<int>> &AR, int &leafs)
{
for (int i = 0; i < AR[x].size(); i++)
{
if (AR[x][i] == p)
continue;
dfs2(AR[x][i], x, AR, leafs);
}
if (AR[x].size() == 1)
leafs++;
}
int main()
{
int N, K;
cin >> N >> K;
vector<vector<int>> AR(N);
for (int i = 0; i < N - 1; i++)
{
int a, b;
cin >> a >> b;
a--, b--;
AR[a].push_back(b);
AR[b].push_back(a);
}
vector<vector<int>> groups(K);
vector<int> Tab(N);
lead.assign(N, 0);
for (int i = 0; i < N; i++)
lead[i] = i;
for (int i = 0; i < N; i++)
{
cin >> Tab[i];
Tab[i]--;
groups[Tab[i]].push_back(i);
}
vector<int> depth(N), p(N), occ(N);
dfs(0, 0, AR, depth, p, 0);
for (int i = 0; i < K; i++)
{
while (groups[i].size() > 1)
{
int a = groups[i].back();
groups[i].pop_back();
int b = groups[i].back();
groups[i].pop_back();
if (occ[a] || occ[b])
{
if (occ[a] == 0)
groups[i].push_back(a), occ[a] = 0;
if (occ[b] == 0)
groups[i].push_back(b), occ[b] = 0;
continue;
}
occ[a] = 1, occ[b] = 1;
while (a != b)
{
if (depth[b] > depth[a])
swap(a, b);
int next = find(p[a]);
occ[next] = 1;
if (Tab[next] > i)
{
for (auto val : groups[Tab[next]])
groups[i].push_back(val);
groups[Tab[next]].clear();
}
if (AR[next].size() < AR[a].size())
swap(AR[next], AR[a]);
for (auto val : AR[a])
AR[next].push_back(val);
lead[a] = next;
a = next;
}
occ[a] = 0;
groups[i].push_back(a);
}
}
for (int i = 0; i < N; i++)
{
if (occ[i])
continue;
for (int j = 0; j < AR[i].size(); j++)
{
AR[i][j] = find(AR[i][j]);
if (AR[i][j] == i)
{
swap(AR[i][j], AR[i].back());
AR[i].pop_back();
j--;
}
}
sort(AR[i].begin(), AR[i].end());
for (int j = 1; j < AR[i].size(); j++)
{
if (AR[i][j] == AR[i][j - 1])
{
swap(AR[i][j], AR[i].back());
AR.pop_back();
j--;
}
}
}
int leafs = 0;
dfs2(find(0), find(0), AR, leafs);
if (leafs == 1)
cout << 0;
else
cout << leafs / 2 + leafs % 2;
}
