/* Problem URL: https://cses.fi/problemset/task/1686 */

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template <class T, class comp = less<>>
using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;

#define V vector

#define rmin(a, b) a = min(a, b)
#define rmax(a, b) a = max(a, b)

#define rep(i, lim) for (int i = 0; i < (lim); i++)
#define nrep(i, s, lim) for (int i = s; i < (lim); i++)

#define repv(i, v) for (auto &i : (v))
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
#define sortv(v) sort(v.begin(), v.end())
#define all(v) (v).begin(), (v).end()

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;

using ll = long long;

using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;

template<class v>
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
    os << vec[0];
    for (size_t i = 1; i < vec.size(); i++) {
        os << ' ' << vec[i];
    }
    os << '\n';
    return os;
}

template<class v>
auto operator>>(istream &is, vector<v> &vec)->istream& {
    for (auto &i : vec) {
        is >> i;
    }
    return is;
}

template<class v>
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
    for (auto &i : vec) {
        os << i[0];
        for (size_t j = 1; j < i.size(); j++) {
            os << ' ' << i[j];
        }
        os << '\n';
    }
    return os;
}

template<class v>
auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
    for (auto &i : vec) {
        for (auto &j : i) {
            is >> j;
        }
    }
    return is;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m;
    cin >> n >> m;

    vl val(n);
    cin >> val;

    vvi graph(n);
    vvi inv(n);

    while (m--) {
        int a, b;
        cin >> a >> b;
        a--, b--;

        graph[a].push_back(b);
        inv[b].push_back(a);
    }

    vi order;
    V<bool> vis(n);

    function<void(int)> preorder = [&](int i) {
        vis[i] = true;

        for (auto j : graph[i]) {
            if (vis[j]) {
                continue;
            }

            preorder(j);
        }

        order.push_back(i);
    };

    rep(i, n) {
        if (vis[i]) {
            continue;
        }

        preorder(i);
    }

    reverse(all(order));
    fill(all(vis), false);

    vi group(n);
    vl costs;
    V<set<int>> cond_graph;
    int g = 0;

    function<void(int)> scc = [&](int i) {
        vis[i] = true;

        group[i] = g;
        costs[g] += val[i];

        for (auto j : inv[i]) {
            if (vis[j]) {
                if (group[j] != group[i]) {
                    cond_graph[group[j]].insert(group[i]);
                }
                continue;
            }

            scc(j);
        }
    };

    repv(i, order) {
        if (vis[i]) {
            continue;
        }

        cond_graph.emplace_back();
        costs.emplace_back();
        scc(i);
        g++;
    }

    vl memo(g, -1);
    
    function<ll(int)> dfs = [&](int i) {
        ll &ans = memo[i];
        if (ans != -1) {
            return ans;
        }

        ans = costs[i];
        for (auto j : cond_graph[i]) {
            rmax(ans, dfs(j) + costs[i]);
        }

        return ans;
    };

    ll ans = 0;
    rep(i, g) {
        rmax(ans, dfs(i));
    }

    cout << ans << '\n';
}