/// Gheorghies Alexandru
#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pld;


const ll LGMAX=20,NMAX=5e5+5;
ll dp[NMAX],deg[NMAX];
vector<ll> edg[NMAX];
void tc(){
    ll n,s=0,ans=LLONG_MAX;
    cin>>n;
    for(ll i=1;i<=n;i++) cin>>dp[i],s+=dp[i];
    for(ll i=0;i<n;i++){
        ll u,v; cin>>u>>v;
        edg[u].push_back(v);
        edg[v].push_back(u);
        deg[u]++,deg[v]++;
    }
    queue<ll> q;
    for(ll i=1;i<=n;i++)
        if(deg[i]==1)
            q.push(i);
    while(!q.empty()){
        deg[q.front()]=0;
        ans=min(ans,abs(2*dp[q.front()]-s));
        for(auto it : edg[q.front()]){
            if(deg[it]>0){
                dp[it]+=dp[q.front()];
                deg[it]--;
                if(deg[it]==1)
                    q.push(it);
            }
        }
        q.pop();
    }
    vector<ll> cycle;
    for(ll i=1;i<=n;i++){
        if(deg[i]>0){
            cycle={i};
            deg[i]=0;
            break;
        }
    }
    while(1){
        bool ok=0;
        for(auto it : edg[cycle.back()]){
            if(deg[it]){
                cycle.push_back(it);
                deg[it]=0;
                ok=1;
                break;
            }
        }
        if(!ok) break;
    }
    n=cycle.size();
    ll l=0,r=n-1,curr=0;
    for(ll l=0;l<n;l++){
        while(1){
            ll nxt=cycle[(r+1)%n];
            if((curr+dp[nxt])*2<=s)
                curr+=dp[nxt],r=(r+1)%n;
            else break;
        }
        ans=min(ans,abs(curr*2-s));
        ll nxt=cycle[(r+1)%n];
        ans=min(ans,abs((curr+dp[nxt])*2-s));
        curr-=dp[cycle[l]];
    }
    cout<<ans;
}
int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif // ONLINE_JUDGE
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    //ll t; cin>>t; while(t--)
        tc();
    return 0;
}