#include<iostream>

#include<cstdio>

#include<cstring>

#include<cmath>

#include<cstdlib>

#include<queue>

using namespace std;

const int MAXN = ;

const int MAXM = ;

inline int rd(){

    int x=,f=;char ch=getchar();

    while(!isdigit(ch)) {f=ch=='-'?:;ch=getchar();}

    while(isdigit(ch))  {x=(x<<)+(x<<)+ch-'';ch=getchar();}

    return f?x:-x;

}

int n,m,head[MAXN],cnt,to[MAXM],nxt[MAXM],w[MAXN],wt[MAXN],ans;

int head_[MAXN],cnt_,to_[MAXM],nxt_[MAXM],du[MAXN],f[MAXN];

int dfn[MAXN],low[MAXN],num,stk[MAXN],top,col_num,col[MAXN];

bool vis[MAXN];

queue<int> Q;

inline void add(int bg,int ed){

    to[++cnt]=ed,nxt[cnt]=head[bg],head[bg]=cnt;

}

void tarjan(int x){

    dfn[x]=low[x]=++num;

    stk[++top]=x;vis[x]=;

    for(register int i=head[x];i;i=nxt[i]){

        int u=to[i];

        if(!dfn[u]) tarjan(u),low[x]=min(low[x],low[u]);

        else if(vis[u]) low[x]=min(dfn[u],low[x]);

    }

    if(low[x]!=dfn[x]) return;col_num++;

    while(stk[top]!=x) {

        wt[col_num]+=w[stk[top]];

        vis[stk[top]]=;

        col[stk[top--]]=col_num;

    }top--;

    vis[x]=;col[x]=col_num;wt[col_num]+=w[x];

}

inline void add_(int bg,int ed){

    to_[++cnt_]=ed,nxt_[cnt_]=head_[bg],head_[bg]=cnt_;

}

int main(){

    n=rd(),m=rd();int x,y,u;

    for(int i=;i<=n;i++) w[i]=rd();

    for(int i=;i<=m;i++){

        x=rd(),y=rd();

        add(x,y);

    }

    for(int i=;i<=n;i++) if(!dfn[i]) tarjan(i);

    for(int i=;i<=n;i++)

        for(int j=head[i];j;j=nxt[j]){

            u=to[j];

            if(col[u]!=col[i]) add_(col[i],col[u]),du[col[u]]++;

        }

    for(int i=;i<=col_num;i++) if(!du[i]) Q.push(i),f[i]=wt[i];

    while(!Q.empty()){

        int x=Q.front();Q.pop();

        for(int i=head_[x];i;i=nxt_[i]){

            int u=to_[i];

            f[u]=max(f[u],f[x]+wt[u]);

            du[u]--;if(!du[u]) Q.push(u);

        }

    }

    for(int i=;i<=col_num;i++) ans=max(ans,f[i]);

    printf("%d",ans);

    return ;

}