如题，我觉得是拓扑的锅

// Tarjan 模板
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MAXX 10005
int n, m, x[MAXX * 10], y[MAXX * 10];
vector<int> t[MAXX], f[MAXX];  // 原图 缩点后图
stack<int> stk;                // 栈
int val[MAXX], sum[MAXX], dfsn[MAXX], low[MAXX], scc[MAXX], instk[MAXX], cnt;
// 点权 连通块权值和 dfs编号 最早到的点 所在强连通块编号 是否在块内 总数
int su[MAXX], ma[MAXX], ans;    // 记录入度 单点值 答案
void Tarjan(int pos, int tp) {  // 点 编号
  dfsn[pos] = low[pos] = tp;
  stk.push(pos), instk[pos] = 1;
  for (auto it : t[pos]) {
    if (dfsn[it] == 0)
      Tarjan(it, tp + 1), low[pos] = min(low[pos], low[it]);
    else if (instk[it])
      low[pos] = min(low[pos], dfsn[it]);  // 注意!!!
  }
  if (dfsn[pos] == low[pos]) {
    cnt++;
    int top;
    do {
      top = stk.top(), stk.pop();
      instk[top] = 0, sum[cnt] += val[top], scc[top] = cnt;
    } while (top != pos);
  }
}
inline ll read();
int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; ++i) val[i] = read();
  for (int i = 1; i <= m; ++i)
    x[i] = read(), y[i] = read(), t[x[i]].push_back(y[i]);
  // 缩点:Tarjan
  for (int i = 1; i <= n; ++i)
    if (!dfsn[i]) Tarjan(i, 1);
  for (int i = 1; i <= m; ++i)
    if (scc[x[i]] != scc[y[i]])
      f[scc[x[i]]].push_back(scc[y[i]]), su[scc[y[i]]]++;
  // 权值计算:拓扑排序
  queue<int> q;  // 入度为0的点
  for (int i = 1; i <= cnt; i++)
    if (su[i] == 0) q.push(i);
  while (!q.empty()) {
    int qwe = q.front();
    q.pop();
    for (auto it : f[qwe]) {
      su[it]--, ma[it] = max(ma[it], ma[qwe] + sum[qwe]);
      if (su[it] == 0) q.push(it);
    }
  }
  for (int i = 1; i <= cnt; i++) ans = max(ans, ma[i] + sum[i]);
  cout << ans << endl;
  return 0;
}
inline ll read() {
  ll k = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') k = k * 10 + ch - '0', ch = getchar();
  return k * f;
}