// compile: make data
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) _debug_print(#x, x);
#define Debug(x...) _debug_print_format(#x, x);
#else
#define debug(x...)
#define Debug(x...)
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define VI vector<int>
#define VII vector<vector<int>>
#define VIII vector<vector<vector<int>>>
#define rep(i,a,b) for(int i=(a);i<(int)(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define FIND(a, x) ((find(a.begin(),a.end(),(x))!=a.end())?1:0)
#define cmin(x,...) x=min({(x), __VA_ARGS__})
#define cmax(x,...) x=max({(x), __VA_ARGS__})
#define INTMAX (int)(9223372036854775807)
#define INF (int)(1152921504606846976)
#define double long double
#define int long long
#define MAXN 200010

struct graph {
    struct node {
        int v, w;
        bool operator<(const node &other) const {
            return w < other.w;
        }
        bool operator==(const node &other) const {
            return v == other.v && w == other.w;
        }
    };
    vector<vector<node>> e;
    int n;
    bool directed;
    graph(int V, bool D = 0) {
        n = V;
        e.resize(n);
        directed = D;
    }
    void add_edge(int u, int v, int w = 1) {
        e[u].push_back(node{v, w});
    }
    void tarjan_scc(vector<vector<int>> &scc, vector<int> &belong) {
        stack<int> s;
        vector<int> dfn(n), low(n), instack(n);
        int dfncnt;
        scc.clear(), belong.resize(n, -1);
        function<void(int)> dfs = [&](int u) {
            low[u] = dfn[u] = ++dfncnt, s.push(u), instack[u] = 1;
            for (auto edge: e[u]) {
                int v = edge.v;
                if (!dfn[v]) dfs(v), cmin(low[u], low[v]);
                else if (instack[v]) cmin(low[u], dfn[v]);
            }
            if (dfn[u] == low[u]) {
                scc.push_back(vector<int>{});
                while (s.top() != u) {
                    belong[s.top()] = sz(scc) - 1;
                    scc.back().push_back(s.top());
                    instack[s.top()] = 0, s.pop();
                }
                belong[s.top()] = sz(scc) - 1;
                scc.back().push_back(s.top());
                instack[s.top()] = 0, s.pop();
            }
        };
        rep(i, 0, n) if (!~belong[i]) dfs(i);
    }
    int topo(vector<int> &vs) {
        vector<int> din(n, 0);
        for (auto es: e) for (auto edge: es) ++din[edge.v];
        queue<int> q;
        rep(i, 0, n) if (!din[i]) q.push(i);
        vs.clear();
        while (!q.empty()) {
            int u = q.front(); q.pop();
            vs.push_back(u);
            for (auto [v, _]: e[u]) {
                if (!--din[v]) q.push(v);
            }
        }
        return sz(vs) == n;
    }
    graph contract(vector<vector<int>> &scc, vector<int> &belong) {
        tarjan_scc(scc, belong);
        int V = sz(scc);
        graph dag(V, 1);
        vector<int> vis(V, 0);
        for (auto comp: scc) {
            for (auto u: comp) {
                for (auto edge: e[u]) {
                    int v = edge.v;
                    if (belong[u] != belong[v]) {
                        dag.add_edge(belong[u], belong[v]);
                        vis[belong[v]] = 1;
                    }
                }
            }
            for (auto u: comp) for (auto edge: e[u]) if (belong[u] != belong[edge.v]) vis[belong[edge.v]] = 0;
        }
        return dag;
    }
    void graphviz_dump(string filename = "graph.dot") {
        ofstream gf; gf.open(filename);
        gf << (directed ? "digraph" : "graph") << " {\n";
        gf << "    "; rep(i, 0, n) gf << i << " ;"[i==n-1]; gf << endl;
        string notation = directed ? " -> " : " -- ";
        bool weighted = 0;
        for (auto es: e) for (auto edge: es) if (edge.w != 1) weighted = 1;
        rep(u, 0, n) {
            for (auto [v, w]: e[u]) {
                if (!directed && u > v) continue;
                gf << "    " << u << notation << v << (weighted ? " ;\n" : ";\n");
            }
        }
        gf << "}\n";
    }
};


int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int n, m; cin >> n >> m;
    vector<int> key(n);
    graph g(n, 1);
    rep(i, 0, n) cin >> key[i];
    rep(i, 0, m) {
        int u, v; cin >> u >> v; --u, --v;
        g.add_edge(u, v);
    }
    vector<vector<int>> scc;
    vector<int> belong;
    auto dag = g.contract(scc, belong);
    vector<int> dagkey(dag.n, 0);
    rep(i, 0, sz(scc)) {
        for (auto u: scc[i]) dagkey[i] += key[u];
    }
    auto ans = dagkey;
    vector<int> vs;
    dag.topo(vs);
    for (auto u: vs) {
        for (auto edge: dag.e[u]) {
            int v = edge.v;
            cmax(ans[v], ans[u] + dagkey[v]);
        }
    }
    cout << *max_element(ans.begin(), ans.end()) << endl;

    return 0;
}