#include <bits/stdc++.h>
using namespace std; 
const int N = 200005; 

int n, k, ans, a[N], bel[N], hit[N]; 
vector<int> G[N]; 
int sz[N], rt, vis[N], mx[N], f[N]; 
vector<int> col[N]; 

void froot(int x, int fa, int tot) {
    sz[x] = 1; 
    for (int y : G[x]) if (y != fa && !vis[y]) froot(y, x, tot), sz[x] += sz[y], mx[x] = max(mx[x], sz[y]); 
    mx[x] = max(mx[x], tot - sz[x]); 
    if (mx[x] < mx[rt]) rt = x; 
}
void inTree(int x, int fa, int anc) {
    f[x] = fa, bel[x] = anc; 
    for (int y : G[x]) if (y != fa && !vis[y]) inTree(y, x, anc); 
}

void divide(int x) {
    // 覆盖所有含 x 的颜色
    vis[x] = 1; inTree(x, 0, x); 
    queue<int> q; q.push(a[x]); 
    int cnt = 0; 
    while (!q.empty()) {
        int c = q.front(); q.pop(); ++cnt; hit[c] = x; 
        // if (x == 3) cout << c << "\n"; 
        for (int i : col[c]) {
            if (bel[i] != x) goto fail; 
            if (f[i] && hit[a[f[i]]] != x) q.push(a[f[i]]); 
        }
    }
    ans = min(ans, cnt); 
    // cout << "G " << x << " " << cnt << "\n"; 
fail:
    for (int y : G[x]) if (!vis[y]) rt = 0, froot(y, x, sz[y]), divide(rt); 
}

int main(void) {
    ios::sync_with_stdio(0); 
    cin >> n >> k; mx[0] = 1e9; ans = k; 
    for (int i = 1, u, v; i < n; ++i) cin >> u >> v, G[u].emplace_back(v), G[v].emplace_back(u); 
    for (int i = 1; i <= n; ++i) cin >> a[i], col[a[i]].emplace_back(i); 
    froot(1, 0, n); divide(rt); 
    cout << ans - 1 << "\n"; 
    return 0; 
}