#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int N;
  cin>>N;
  vector<int> A(N),B(N);
  double a=0,b=0;
  for(int i=0;i<N;i++){
      cin>>A[i];
      a += A[i];
  }
  for(int i=0;i<N;i++){
      cin>>B[i];
      b += B[i];
  }
  double aa=a,bb=b;
  double ans = 0;
  double now = 1;
  for(int i=0;i<N;i++){
      if(sqrt(aa*bb) < aa && bb < sqrt(aa*bb) && A[i]/now > B[i]*now){
          now = max(now,aa/sqrt(aa*bb));
      }
      ans += A[i]/now;
      ans += B[i]*now;
      a -= A[i];
      b -= B[i];
      aa = a/now;
      bb = b*now;
  }
  cout<<fixed<<setprecision(12);
  cout<<ans<<endl;
}