#include <bits/stdc++.h>

using namespace std;

const int N = 2e5 + 5;
const int SIZE = 1800005; 
const int SIZEY = 32400005; 
int n, c[N];
vector<int> pos[N], tr[N];
int dep[N], fa[N], st[N], ed[N], cnt;

void dfs(int u, int pre) {
	st[u] = ++cnt;
	dep[u] = dep[pre] + 1;
	fa[u] = pre;
	for (int v : tr[u])
		if (v != pre)
			dfs(v, u);
	ed[u] = cnt;
}

int spt[18][N];

inline int LCA(int x, int y) {
	if (x == y) return x;
	int l = st[x], r = st[y];
	if (l > r) swap(l, r);
	++l;
	int k = __lg(r - l + 1);
	x = spt[k][l], y = spt[k][r - (1 << k) + 1];
	return fa[dep[x] < dep[y] ? x : y];
}

inline int son(int x, int y) {
	int l = st[x], r = st[y];
	++l;
	int k = __lg(r - l + 1);
	x = spt[k][l], y = spt[k][r - (1 << k) + 1];
	return (dep[x] < dep[y] ? x : y);
}

inline int dist(int x, int y) { return dep[x] + dep[y] - 2 * dep[LCA(x, y)]; }
inline bool isanc(int x, int y) { return st[y] >= st[x] && st[y] <= ed[x]; }

int dis[N], id[N], m;

inline bool cmp(int i, int j) { return dis[i] > dis[j]; }

int rt, ls[SIZE], rs[SIZE], tot;
int rty[SIZE], lsy[SIZEY], rsy[SIZEY], val[SIZEY], toty;

void updatey(int &z, int y, int v, int l = 1, int r = n) {
	if (!z) z = ++toty;
	val[z] = max(val[z], v);
	if (l == r) return;
	int mid = (l + r) >> 1;
	if (y <= mid) updatey(lsy[z], y, v, l, mid);
	else updatey(rsy[z], y, v, mid + 1, r);
}

void update(int &z, int x, int y, int v, int l = 1, int r = n) {
	if (!z) z = ++tot;
	updatey(rty[z], y, v);
	if (l == r) return;
	int mid = (l + r) >> 1;
	if (x <= mid) update(ls[z], x, y, v, l, mid);
	else update(rs[z], x, y, v, mid + 1, r);
}

int queryy(int z, int L, int R, int l = 1, int r = n) {
	if (!z) return 0;
	if (L <= l && r <= R) return val[z];
	int mid = (l + r) >> 1, res = 0;
	if (L <= mid) res = max(res, queryy(lsy[z], L, R, l, mid));
	if (R > mid) res = max(res, queryy(rsy[z], L, R, mid + 1, r));
	return res;
}

int query(int z, int U, int D, int L, int R, int l = 1, int r = n) {
	if (!z) return 0;
	if (U <= l && r <= D) return queryy(rty[z], L, R);
	int mid = (l + r) >> 1, res = 0;
	if (U <= mid) res = max(res, query(ls[z], U, D, L, R, l, mid));
	if (D > mid) res = max(res, query(rs[z], U, D, L, R, mid + 1, r));
	return res;
}

inline int ask(int U, int D, int L, int R) {
	if (U > D || L > R) return 0;
	return query(rt, U, D, L, R);
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n;
	for (int i = 1; i <= n; ++i) cin >> c[i], pos[c[i]].push_back(i);
	for (int i = 1; i < n; ++i) {
		int u, v;
		cin >> u >> v;
		tr[u].push_back(v);
		tr[v].push_back(u);
	}
	dfs(1, 0);
	for (int i = 1; i <= n; ++i) spt[0][st[i]] = i;
	for (int i = 1; (1 << i) <= n; ++i)
		for (int j = 1; j + (1 << i) - 1 <= n; ++j) {
			int x = spt[i - 1][j], y = spt[i - 1][j + (1 << (i - 1))];
			spt[i][j] = (dep[x] < dep[y] ? x : y);
		}
	for (int i = 1; i <= n; ++i) {
		if (pos[i].size() < 2u) continue;
		id[++m] = i;
		dis[i] = dist(pos[i][0], pos[i][1]);
		if (st[pos[i][0]] > st[pos[i][1]]) swap(pos[i][0], pos[i][1]);
	}
	sort(id + 1, id + m + 1, cmp);
	int ans = 0;
	for (int o = 1; o <= m; ++o) {
		int i = id[o];
		if (isanc(pos[i][0], pos[i][1])) {
			int s = son(pos[i][0], pos[i][1]);
			int res = max(ask(1, st[s] - 1, st[pos[i][1]], ed[pos[i][1]]), ask(st[pos[i][1]], ed[pos[i][1]], ed[s] + 1, n)) + 2;
			update(rt, st[pos[i][0]], st[pos[i][1]], res);
			ans = max(ans, res);
		} else {
			int res = ask(st[pos[i][0]], ed[pos[i][0]], st[pos[i][1]], ed[pos[i][1]]) + 2;
			update(rt, st[pos[i][0]], st[pos[i][1]], res);
			ans = max(ans, res);
		}
	}
	for (int u = 1; u <= n; ++u) {
		for (int v : tr[u])
			if (v != fa[u])
				ans = max(ans, ask(st[u] + 1, st[v] - 1, st[v], ed[v]) + 1);
		ans = max(ans, ask(1, st[u] - 1, st[u] + 1, ed[u]) + 1);
		ans = max(ans, ask(st[u] + 1, ed[u], ed[u] + 1, n) + 1);
	}
	cout << ans << '\n';
	return 0;
}