#include<bits/stdc++.h>
using namespace std;

const int N=1e5+5;

int n , m , a[N];
int u , v;
vector<int> vc[N];
int dfn[N] , low[N] , cnt;
bool vis[N];
stack<int> st;
int belong_cnt; //强连通分量个数 
vector<int> belong[N];//强连通分量 
int color[N];//color[i]表示第i头牛所处的强连通分量  
vector<int> newvc[N];
int in[N];//入度 
int ans[N];
void tarjan(int u)
{
	dfn[u] = low[u] = ++cnt;
	vis[u] = 1;
	st.push(u);
	for(int i = 0; i < vc[u].size(); i++)
	{
		int v = vc[u][i];
		if(!dfn[v])
		{
			tarjan(v);
			low[u] = min(low[u] , low[v]);
		}
		else if(vis[v])
		{
			low[u] = min(low[u] , low[v]);
		}	
	}
	//强连通分量到头	
	if(dfn[u] == low[u])
	{
		while(!st.empty())
		{
			v = st.top();
			st.pop();
			vis[v] = 0;
			color[v] = u;//当前牛所处的强连通分量 
			if(u == v) break;
			a[u] += a[v];
		}
	}
}

void tupo()
{
	queue<int> q;
	for(int i = 1; i <= n; i++)
	{
		if(color[i] == i && !in[i])
		{
			q.push(i);
			ans[i] = a[i];
		}
	}
	
	while(!q.empty())
	{
		int top = q.front();
		q.pop();
		
		for(int i = 0; i < newvc[top].size(); i++)
		{
			v = newvc[top][i];
			ans[v] = max(ans[v] , ans[top] + a[v]);
			in[v]--;
			if(!in[v])
				q.push(v);
		}
	}
	
	int maxx = 0;
	for(int i = 1; i <= n; i++)
		maxx = max(maxx , ans[i]);
	cout << maxx;
}

int main(){
	cin >> n >> m;
	for(int i = 1; i <= n; i++)
		cin >> a[i];
	while( m-- )
	{
		cin >> u >> v;
		vc[u].push_back(v); 
	}
	for(int i = 1; i <= n; i++)
		if(!dfn[i])
			tarjan(i);
	
	//重新建边
	for(int i = 1; i <= n; i++)
	{
		for(int j = 0; j < vc[i].size(); j++)
		{
			v = vc[i][j];
			if(color[i] != color[v])
			{
				newvc[color[i]].push_back(color[v]);
				in[color[v]]++; 
			}	
		}	
	} 
	
	tupo();
	
	return 0;