#include <iostream>
#include <cstdio>
using namespace std;
const int NMAX = 16000;

bool visited[NMAX+1];
int last[NMAX+1],urm[NMAX+1],vf[NMAX+1],nr;
int v[NMAX+1];

void adauga(int x, int y){
    vf[++nr] = y;
    urm[nr] = last[x];
    last[x] = nr;
}

void dfs(int nod){
    visited[nod] = true;
    for(int p=last[nod]; p!=0; p=urm[p]){
        int next = vf[p];
        if(!visited[next]){
            dfs(next);
            if(v[next] > 0)
                v[nod] += v[next];
        }
    }
}

int main()
{
    FILE *fin, *fout;
    int n,i,x,y;
    fin = fopen("asmax.in","r");
    fout = fopen("asmax.out","w");
    fscanf(fin,"%d",&n);
    for(i=1; i<=n; i++)
        fscanf(fin,"%d",&v[i]);
    for(i=1; i<n; i++){
        fscanf(fin,"%d %d",&x,&y);
        adauga(x,y);
        adauga(y,x);
    }
    dfs(1);
    fprintf(fout,"%d\n",v[1]);
    fclose(fin);
    fclose(fout);
    return 0;
}