A

#include <iostream>
#include <vector>
#include <array>
#include <set>

using namespace std;

#define int long long

const long long INF = 1e18 + 7;
const int MAXN = 6e3 + 100;
const int N = 1e5 + 10;

array<array<int, MAXN>, 2> dp;
array<int, MAXN> cost;
vector<vector<int>> g;

void dfs(int v) {
    for (auto to: g[v]) {
        dfs(to);
        dp[0][v] += max(dp[0][to], dp[1][to]);
        dp[1][v] += dp[0][to];
    }
    dp[1][v] += cost[v];
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> cost[i];
    }
    g.resize(n);
    set<int> st;
    for(int i = 0; i < n; ++i) {
        st.insert(i);
    }
    while (true) {
        int u, v;
        cin >> u >> v;
        if (u == 0 && v == 0) {
            break;
        }
        --u, --v;
        g[v].emplace_back(u);
        st.erase(u);
    }
    int root = *st.begin();
    dfs(root);
    cout << max(dp[0][root], dp[1][root]) << '\n';
}