#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <stack>
#include <vector>
using namespace std;
const int MAX=111111;
int N,E;
int v[MAX];
const int MINF=-210000000;
int in[MAX],out[MAX];
int dp[MAX];
vector<int>g[MAX];
void tuopu()
{
	stack<int>s;
	for(int i=1;i<=N;i++)
	{
		if(in[i]==0)
			s.push(i);
	}
	int tmp=N;
	while(tmp--)
	{
		int now=s.top();s.pop();
		for(int i=0;i<g[now].size();i++)
		{
			dp[g[now][i]]=max(dp[g[now][i]],dp[now]+v[g[now][i]]);
			in[g[now][i]]--;
			if(!in[g[now][i]])
				s.push(g[now][i]);
		}
	}
}
int main()
{
	#ifndef ONLINE_JUDGE
		freopen("G:/1.txt","r",stdin);
		freopen("G:/2.txt","w",stdout);
	#endif
	while(scanf("%d%d",&N,&E)!=EOF)
    {
        for(int i=1;i<=N;i++)
        {
            scanf("%d",&v[i]);
        }
        for(int i=1;i<=E;i++)
        {
            int x,y;
            scanf("%d%d",&x,&y);
            out[x]++;
            in[y]++;
            g[x].push_back(y);
        }
        for(int i=1;i<=N;i++)
        {
            if(in[i]==0)
                dp[i]=v[i];
            else
                dp[i]=MINF;
        }
        tuopu();
        int maxn=MINF;
        for(int i=1;i<=N;i++)
        {
            if(out[i]==0)
                maxn=max(maxn,dp[i]);
        }
        printf("%d\n",maxn);
        for(int i=1;i<=N;i++)
        {
            g[i].clear();
        }
        memset(v,0,sizeof(int)*N);
        memset(in,0,sizeof(int)*N);
        memset(out,0,sizeof(int)*N);
        memset(dp,0,sizeof(int)*N);
    }
	return 0;
}