#include <stdio.h>
#include <stack>
#include <stdlib.h>
#include <iostream>
#include <queue>
#include <algorithm>
#define N 10050
using namespace std;
typedef struct EDGE {
    int next, to;
    int from;
}E;
E edge[N * 20];
E  ed[N*20];
int indu[N];
int h[N];
int root[N];
int num;
void addd(int x, int y) {
    num++;
    ed[num].from = x;
    ed[num].to = y;
    ed[num].next = h[x];
    h[x] = num;
}

int w[N];
int head[20 * N], dfn[N], low[N];
int du[N], id[N];
bool insta[N]; int idx, cnt, n, m;
stack<int>s;
inline void add(int x, int y) {
    cnt++;
    edge[cnt].to = y;
    edge[cnt].from = x;
    edge[cnt].next = head[x];
    head[x] = cnt;
}
void tarjan(int x) {
    dfn[x] = low[x] = ++idx;
    s.push(x);
    insta[x] = 1;
    for (int i = head[x]; i; i = edge[i].next) {
        int v = edge[i].to;
        if (!dfn[v]) {
            tarjan(v);
            low[x] = min(low[v], low[x]);
        }
        else if(insta[v])low[x] = min(dfn[v], low[x]);

    }
    int k ;
    if (dfn[x] == low[x]) {
        do {
            k = s.top();
            s.pop();
            id[k] = x;
            insta[k] = 0;
            if (k == x)break;
            w[x] += w[k];
        } while (k != x);
    } 
}
int Tuopu() {
    queue<int>q;
    int dis[N];
    for (int i = 1; i <= n; i++) {
        if (indu[i] == 0 &&id[i]==i) {
            q.push(i);
            dis[i]=w[i];
        }
        while (!q.empty()) {
            int k = q.front();
            q.pop();
            for (int i = h[k]; i; i = ed[i].next) {
                int v = ed[i].to;
                dis[v] = max(dis[v], dis[k]+w[v]);
                indu[v]--;
                if (indu[v] == 0)q.push(v);
            }
        }
    }
    int ans = 0;
    for (int i = 1; i <= n; i++)
        ans = max(ans, dis[i]);
    return ans;

}
int main() {
    cin >> n >> m;
    int u, v;
    for (int i = 1; i <= n; i++)
        cin >> w[i];
    for (int i = 1; i <= m; i++) {
        cin >> u >> v;
        add(u, v);
    }
    for (int i = 1; i <= n; i++) {
        if (!dfn[i])
            tarjan(i);
    }
    for (int i = 1; i <= m; i++) {
        int x = edge[i].from, y = edge[i].to;
        if (id[x] != id[y])
        {
            addd(id[x], id[y]);
            indu[id[y]]++;
        }
   }
    printf("%d", Tuopu());
    return 0;
}