#include<bits/stdc++.h>

 using namespace std;

 typedef long long ll;

 typedef unsigned int uint;

 typedef unsigned long long ull;

 typedef pair<int,int> PII;

 typedef pair<ll,ll> Pll;

 typedef vector<int> VI;

 typedef vector<PII> VII;

 typedef pair<ll,int>P;

 #define N  2100000

 #define M  151000

 #define fi first

 #define se second

 #define MP make_pair

 #define pi acos(-1)

 #define mem(a,b) memset(a,b,sizeof(a))

 #define rep(i,a,b) for(int i=(int)a;i<=(int)b;i++)

 #define per(i,a,b) for(int i=(int)a;i>=(int)b;i--)

 #define lowbit(x) x&(-x)

 #define Rand (rand()*(1<<16)+rand())

 #define id(x) ((x)<=B?(x):m-n/(x)+1)

 #define ls p<<1

 #define rs p<<1|1

 const ll MOD=1e9+,inv2=(MOD+)/;

       double eps=1e-;

       ll INF=1e18;

       ll inf=5e13;

       int dx[]={-,,,};

       int dy[]={,,-,};

 int l[N],s[N],v[N];

 int read()

 {

    int v=,f=;

    char c=getchar();

    while(c<||<c) {if(c=='-') f=-; c=getchar();}

    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();

    return v*f;

 }

 int main()

 {

     //freopen("1.in","r",stdin);

     //freopen("1.out","w",stdout);

     int n;

     while(scanf("%d",&n)!=EOF)

     {

         rep(i,,n+) l[i]=read();

         rep(i,,n+) s[i]=read();

         rep(i,,n+) v[i]=read();

         double sum=,ans=1.0*s[]/v[];

         rep(i,,n+)

         {

             sum+=l[i];

             ans=max(ans,1.0*(sum+s[i])/v[i]);

         }

         printf("%.10f\n",ans);

     }

     return ;

 }