# include<iostream>
# include<algorithm>
# include<cmath>
# include<iomanip>
# include<stack>
# include<queue>
# define endl "\n"
using namespace std;
const int maxn=10001, maxm=200001;
struct Node{
	int u, v, next;
}edge[maxm], new_edge[maxm];
int n, m, a[maxn], cnt=0, new_cnt=0, head[maxn], new_head[maxn]; 
int dfn[maxn], low[maxn], vis[maxn], color[maxn], tim=0;
stack<int> s; queue<int> q;
int in_new_edge[maxn], dp[maxn], in[maxn], ans=-1;
void add(int u, int v) {
	cnt++;
	edge[cnt].u=u;
	edge[cnt].v=v;
	edge[cnt].next=head[u];
	head[u]=cnt;
}
void new_add(int u, int v) {
	new_cnt++;
	new_edge[new_cnt].u=u;
	new_edge[new_cnt].v=v;
	new_edge[new_cnt].next=new_head[u];
	new_head[u]=new_cnt;
	in[v]++;
}
void tarjan(int u) {
	tim++; dfn[u]=low[u]=tim;
	s.push(u); vis[u]=true;
	for(int i=head[u]; i; i=edge[i].next) {
		int v=edge[i].v;
		if(!dfn[v]) {
			tarjan(v);
			low[u]=min(low[v], low[u]);
		} else low[u]=min(low[u], dfn[v]);
	}
	if(dfn[u]==low[u]) { // 强连通分量 
		while(true) {
			int t=s.top();
			s.pop();
			color[t]=u;
			if(u==t) break;
			else a[u]+=a[t];
		}
	}
}
int main(){
	cin >> n >> m;
	for(int i=1; i<=n; i++) cin >> a[i];
	for(int i=1; i<=m; i++) {
		int u, v; cin >> u >> v;
		add(u, v);
	}
	for(int i=1; i<=n; i++)
		color[i]=i;
	for(int i=1; i<=n; i++)
		if(!dfn[i])
			tarjan(i);
	for(int i=1; i<=m; i++) {
		int u=color[edge[i].u], v=color[edge[i].v];
		if(u!=v) new_add(u, v);
	}
	for(int i=1; i<=n; i++)
		in_new_edge[color[i]]=true; 
	// 拓扑dp
	for(int i=1; i<=n; i++) {
		if(in[i]==0 && in_new_edge[i]) {
			q.push(i);
			dp[i]=a[i];
		}
	} 
	while(!q.empty()) {
		int u=q.front();
		q.pop();
		for(int i=new_head[u]; i; i=new_edge[i].next) {
			int v=new_edge[i].v;
			dp[v]=max(dp[v], dp[u]+a[v]);
			in[v]--;
			if(in[v]==0) q.push(v);
		}
	}
	for(int i=1; i<=n; i++) 
		if(in_new_edge[i])
			ans=max(ans, dp[i]);
	cout << ans << endl;
	return 0;
}

谢谢各位大佬！