#include<bits/stdc++.h>
using namespace std;
int n,m;
int a[10010];
struct edge{
	int x,y,next;
}e[500010],g[500010];
int head[500010],head2[500010],cnt2=0,cnt=0;
int dfn[10010],low[10010],dfncnt,inst[10010],s[10010],tp=0,scc[10010],sc,sz[10010];
int rd[10010];
void insert(int x,int y){
	e[++cnt]={x,y,head[x]};
	head[x]=cnt;
}
void insert2(int x,int y){
	g[++cnt2]={x,y,head2[x]};
	head2[x]=cnt2;
	rd[y]++;
}

void tarjan(int x){
	dfn[x]=low[x]=++dfncnt;
	s[++tp]=x;inst[x]=1;
	for(int i=head[x];~i;i=e[i].next){
		int y=e[i].y;
		if(!dfn[y]){
			tarjan(y);
			low[x]=min(low[x],low[y]);
		}else if(inst[y])low[x]=min(low[x],dfn[y]);
	}
	if(dfn[x]==low[x]){
		++sc;
		do{
			scc[s[tp]]=sc;
			sz[sc]+=a[s[tp]];
			inst[s[tp]]=0;
		}while(s[tp--]!=x);
	}
}
int ans=0,dp[10010];
queue<int> q;
void topo(){
	memset(dp,0,sizeof(dp));

	for(int i=1;i<=sc;i++){
		if(!rd[i]){
			q.push(i);
			dp[i]=sz[i];
		}
	}
	while(!q.empty()){
		int x=q.front();
		q.pop();ans=max(ans,dp[x]);
		for(int i=head2[x];~i;i=g[i].next){
			dp[g[i].y]=max(dp[g[i].y],dp[x]+sz[g[i].x]);
			rd[i]--;
			if(!rd[i])q.push(i);
		}
	}
}

int main(){
	memset(dfn,0,sizeof(dfn));
	memset(inst,0,sizeof(inst));
	memset(head,-1,sizeof(head));
	cin>>n>>m;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<=m;i++){
		int x,y;
		cin>>x>>y;
		insert(x,y);
	}
	for(int i=1;i<=n;i++){
		if(!dfn[i])tarjan(i);
	}
	memset(head2,-1,sizeof(head2));
	memset(rd,0,sizeof(rd));
	for(int i=1;i<=cnt;i++){
		int x=scc[e[i].x],y=scc[e[i].y];
		if(x!=y){
			insert2(x,y);
		}
	}
	topo();
	cout<<ans;
	return 0;
}