cutdrope.txt

import java.util.ArrayList;
import java.util.Scanner;


public class Solution {

	static int n;
	static int a[];
	static ArrayList<Integer> e[];
	static int ans = Integer.MAX_VALUE;
	static int sum = 0;
	
	static int dfs(int u, int parent) {
		int acc = a[u];
		
		for (int v : e[u]) {
			if (v == parent) continue;
			
			int cb = dfs(v, u);
			acc += cb;
			ans = Math.min(ans, Math.abs(cb - (sum - cb)));
		}
		
		return acc;
	}
	@SuppressWarnings("unchecked")
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner cin = new Scanner(System.in);
		n = cin.nextInt();
		a = new int[n];
		e = new ArrayList[n];
		for (int i=0; i<n; i++) {
			a[i] = cin.nextInt();
			sum += a[i];
			e[i] = new ArrayList<Integer>();
		}
		
		for (int i=0; i<n-1; i++) {
			int u = cin.nextInt() - 1;
			int v = cin.nextInt() - 1;
			e[u].add(v);
			e[v].add(u);
		}
		
		dfs(0, -1);
		System.out.println(ans);
	}

}