#include <vector>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define MAXN 110000
#define vint vector<int> 

using namespace std;
int n,m;
vint son[MAXN];
int dp[MAXN][2];
int a[MAXN];

void merge(int x[],int y[]){
    int ret[2];
    ret[0] = max(x[0]+y[0],x[1]+y[1]);
    ret[1] = max(x[0]+y[1],x[1]+y[0]);
    x[0]=ret[0];
    x[1]=ret[1];
}

void dfs(int x,int fa){
    if(x!=1 && son[x].size()==1){
        dp[x][0] = a[x];
        dp[x][1] = 1^a[x];
        return;
    }
    int t[2]={-1,-1};
    for(auto &v:son[x]){
        if(v==fa)continue;
        dfs(v,x);
        if(t[0]==-1){
            t[0]=dp[v][0];
            t[1]=dp[v][1];
        }
        else{
            merge(t,dp[v]);
        }
    }
    dp[x][0] = t[0] + a[x];
    dp[x][1] = t[1] + (1^a[x]);
}

int main(){

    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%d",&a[i]);
    }
    for(int i=1;i<n;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        son[x].push_back(y);
        son[y].push_back(x);
    }

    dfs(1,0);

    cout<<max(dp[1][0],dp[1][1])<<endl;

    return 0;
}