#include <iostream>
#include <vector>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <string>
#include <cstring>
#include <queue>
#include <stack>
#include <functional>
#include <map>
#include <set>
#include <bitset>
#include <ctime>
#include <cassert>
#include <complex>

const int INF = 0x3f3f3f3f;
const long long INFLL = 0x3f3f3f3f3f3f3f3fll;
#define memset0(x) memset(x, 0, sizeof(x))
#define memsetM1(x) memset(x, -1, sizeof(x))
#define memsetINF(x) memset(x, INF, sizeof(x))

using namespace std;

int n;
const int MAXN = 1e5 + 5;
vector<int> edge[MAXN];
int color[MAXN];
int dp[MAXN][2];
bool vis[MAXN];

void dfs(int u)
{
	for (auto v : edge[u])
	{
		if (!vis[v])
		{
			vis[v] = true;
			dfs(v);
			vis[v] = false;
		}
		
	}
	int ans0 = 0;
	int ans1 = -INF;
	for (auto v : edge[u])
	{
		if (!vis[v])
		{
			int tmpans0 = max(ans0 + dp[v][0], ans1 + dp[v][1]);
			int tmpans1 = max(ans1 + dp[v][0], ans0 + dp[v][1]);
			ans0 = tmpans0;
			ans1 = tmpans1;
		}
		
	}
	dp[u][0] = ans0 + color[u];
	dp[u][1] = max(ans1 + 1 - color[u], 1 - color[u]);
	
}

int main()
{
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		scanf("%d", &color[i]);
	}
	for (int i = 0; i < n - 1; i++)
	{
		int u, v;
		scanf("%d%d", &u, &v);
		edge[u].push_back(v);
		edge[v].push_back(u);
	}
	vis[1] = true;
	dfs(1);
	cout << max(dp[1][0], dp[1][1]) << endl;

	return 0;
}