[[http://acm.hdu.edu.cn/showproblem.php?pid=6581|HDU6581]]

<code cpp>
#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cmath>
#define LL long long
using namespace std;
const int N=1e5+10;
int n;
LL l[N],s[N],v[N];
int read()
{
	int x=0,f=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
	while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
	return x*f;
}
int main()
{
	while(~scanf("%d",&n))
	{
		LL len=0;
		double mint=0;
		for(int i=0;i<=n;i++)l[i]=read();
		for(int i=0;i<=n;i++)s[i]=read();
		for(int i=0;i<=n;i++)v[i]=read();
		for(int i=0;i<=n;i++)
		{
			if(!i)mint=s[i]*1.0/v[i];
			else len+=l[i],mint=max(mint,((s[i]+len)*1.0)/v[i]);
		}
		printf("%.10lf\n",mint);
	}
	return 0;
}

</code>