$$ Tarjan $$

#include<queue>
#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

const int N = 1e4 + 12;
#define re register 

int n, m, idx, tim, top, s; // tim (dfs) 次数 
int head[N], p[N], sd[N], dfn[N], low[N];
int stac[N], st[N];
int h[N], in[N], dis[N];

struct node{
    int to;
    int from;
    int next;
}edge[N << 3], ed[N << 3];

void add(int u, int v){
    edge[++idx].to = v;
    edge[idx].from = u;
    edge[idx].next = head[u];
    head[u] = idx;
}

void Tarjan(int u){
    low[u] = dfn[u] = ++tim;
    stac[++ top] = u;
    st[u] = 1;

    for(re int i = head[u]; i; i = edge[i].next)
    {
        int v = edge[i].to;
        if(!dfn[v]){
            Tarjan(v);
            low[u] = min(low[u], low[v]);
        }
        else if(st[v]){
            low[u] = min(low[u], low[v]);
        }
    }

    if(dfn[u] == low[u]){
        int y;
        while(y = stac[top --]){
            sd[y] = u;
            st[y] = 0;
            if(u == y) break;
            p[u] += p[y];
        }
    }
}

int topo()
{
    queue<int>q;
    int tot = 0;
    for(re int i = 1;i <= n;i ++)
        if(sd[i] == i && !in[i])
            q.push(i),dis[i] = p[i];
    while(!q.empty())
    {
        int u = q.front();
        q.pop();
        for(re int i = h[u]; i; i = ed[i].next)
        {
            int v = ed[i].to;
            dis[v] = max(dis[v], dis[u] + p[v]);
            in[v] --;
            if(in[v] == 0)
                q.push(v);
        }
    }

    int ans = 0;
    for(re int i = 1;i <= n;i ++)
        ans = max(ans, dis[i]);

    return ans;
}

int main()
{
    scanf("%d%d",&n,&m);
    for(re int i = 1;i <= n;i ++) scanf("%d",&p[i]);
    for(re int i = 1;i <= m;i ++)   {
        int u, v;
        scanf("%d%d",&u, &v);
        add(u,v);
    }

    for(re int i = 1;i <= n;i ++)
        if(!dfn[i]) Tarjan(i);

    for(re int i = 1;i <= m;i ++){
        int u = sd[edge[i].from],v = sd[edge[i].to];
        if(u != v){
            ed[++s].next = h[u];
            ed[s].to = v;
            ed[s].from = u;
            h[u] = s;
            in[v] ++;
        }
    }

    printf("%d\n", topo());

    return 0;
}