> #include<stdio.h>
> #include<string.h>
> #define maxn 100005
> int n,m;
> int v[maxn];
> struct node
> {int vex;
>  node * next;
> };
> node * side[maxn];
> 
> int que[maxn];
> int ind[maxn];
> int outd[maxn];
> int res[maxn];
> int mark[maxn];
> 
> int max(int a,int b)
> {return a>b?a:b;
> }
> void bfs()
> {
> 	int closed=-1,open=-1;
> 	memset(mark,0,sizeof(mark));
> 	int i,j;
> 	for(j=1;j<=n;j++)
> 		res[j]=v[j];
> 
> 	for(i=1;i<=n;i++)
> 		if(outd[i]==0){
> 			closed++;
> 			que[closed]=i;
> 			mark[i]=1;
> 		}
> 	while(open<closed)
> 	{
> 		open++;
> 		j=que[open];
> 		node *p=side[j];
> 		while(p!=NULL)
> 		{
> 			i=p->vex;
> 			res[i]=max(res[i],res[j]+v[i]);
> 			if(!mark[i]){
> 				closed++;
> 				que[closed]=i;
> 				mark[i]=1;
> 			}
> 			p=p->next;
> 		}
> 	}
> }
> 
> int main()
> {
> 	//freopen("file.in","r",stdin);
> 
> 	int i,j,k;
> 
> 	while(scanf("%d%d",&n,&m)!=EOF)
> 	{
> 		for(i=1;i<=n;i++){
> 			scanf("%d",&v[i]);
> 		}
> 		memset(ind,0,sizeof(ind));
> 		memset(outd,0,sizeof(outd));
> 		for(i=1;i<=n;i++) {
> 			side[i]=NULL;
> 		}
> 		for(k=0;k<m;k++)
> 		{
> 			scanf("%d%d",&i,&j);
> 			ind[j]++;
> 			outd[i]++;
> 			node *q;
> 			q=new node;
> 			q->vex=i;
> 			q->next=side[j];
> 			side[j]=q;
> 		}
> 
> 		int best=-0x7fffffff;
> 		bfs();
> 		for(k=1;k<=n;k++)
> 			if(ind[k]==0){
> 				best=max(best,res[k]);
> 			}
> 		printf("%d\n",best);
> 	}
>    return 0;
> }
> 
> 
> 
> 
> 
>