#include <bits/stdc++.h>


using namespace std;


#define ll long long
#define ld long double
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()


int n, k;
vector<vector<int>> g, anc;
vector<int> c, dep, par;


void dfs(int u, int p = 0) {
    par[u] = p;
    anc[0][u] = p;
    dep[u] = dep[p] + 1;
    for (auto v : g[u]) {
        if (v != p) {
            dfs(v, u);
        }
    }
}


int lca(int a, int b) {
    if (dep[a] < dep[b]) {
        swap(a, b);
    }
    for (int h = 19; h >= 0; h -= 1) {
        if (dep[a] - (1 << h) >= dep[b]) {
            a = anc[h][a];
        }
    }
    if (a == b) {
        return a;
    }
    for (int h = 19; h >= 0; h -= 1) {
        if (anc[h][a] != anc[h][b]) {
            a = anc[h][a];
            b = anc[h][b];
        }
    }
    return anc[0][a];
}


int32_t main() {
    if (1) {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout.tie(0);
	}
	cin >> n >> k;
    g.resize(n + 1);
    for (int i = 1; i < n; i += 1) {
        int a, b;
        cin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    dep.resize(n + 1);
    anc.assign(20, vector<int>(n + 1));
    par.resize(n + 1);
    dfs(1);
    for (int h = 1; h < 20; h += 1) {
        for (int i = 1; i <= n; i += 1) {
            anc[h][i] = anc[h - 1][anc[h - 1][i]];
        }
    }


    c.resize(n + 1);
    vector<vector<int>> occ(n + 1);
    for (int i = 1; i <= n; i += 1) {
        cin >> c[i];
        occ[c[i]].push_back(i);
    }
    vector<int> cnt(k + 1);
    int ans = k;
    for (int i = 1; i <= k; i += 1) {
        int x = occ[i][0];
        for (auto j : occ[i]) {
            x = lca(x, j);
        }
        int f = 0;
        for (auto j : occ[i]) {
            int u = j;
            while (u != x) {
                cnt[c[u]] += 1;
                if (cnt[c[u]] == 1) {
                    f += 1;
                }
                u = par[u];
            }
        }
        ans = min(ans, f - 1);
        for (int j = 1; j <= k; j += 1) {
            cnt[j] = 0;
        }
    }
    cout << ans << "\n";
    return 0;
}