//什么时候我才能有杜爷一半强啊/kk
#include<cstdio>
#include<bitset>
#define int long long
using namespace std;
const int N=705;
int n,m,ans,sum[N],c[N],w[N];
bitset<N>bs[N];
int Max(int a,int b){return a>b?a:b;}
int Min(int a,int b){return a<b?a:b;}
int read(){
	char ch=getchar();int nn=0,ssss=1;
	while(ch<'0'||ch>'9'){if(ch=='-')ssss*=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){nn=nn*10+(ch-'0');ch=getchar();}
	return nn*ssss;
}
signed main(){
	n=read();m=read();
	for(int i=1;i<=n;i++)c[i]=read();
	for(int i=1;i<=n;i++)w[i]=read();
	for(int i=1;i<=m;i++){
		int u=read();int v=read();
		bs[u][v]=true;
	}
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n;j++)
			if(bs[i][j])bs[i]|=bs[j];
	for(int i=1;i<=n;i++){
		if(c[i]!=1)continue;
		for(int j=1;j<=n;j++)sum[j]=0;
		for(int j=1;j<=n;j++)if(bs[i][j])sum[c[j]]+=w[j];
		for(int i=2;i<=n;i++)ans=Max(ans,sum[i]/w[i]);
	}
	printf("%lld",ans);
}