// g++ -std=c++11 a.cpp
#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<unordered_map>
#include<utility>
#include<cmath>
#include<random>
#include<cstring>
#include<queue>
#include<stack>
#include<bitset>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#include<typeinfo>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define FOR(i,a) for(auto i:a)
#define pb push_back
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
#define show1d(v) rep(_,v.size())cout<<" "<<v[_];cout<<endl;
#define show2d(v) rep(_,v.size()){rep(__,v[_].size())cout<<" "<<v[_][__];cout<<endl;}cout<<endl;
using namespace std;
//kaewasuretyuui
typedef long long ll;
//#define int ll
typedef int Def;
typedef pair<Def,Def> pii;
typedef vector<Def> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef pair<Def,pii> pip;
typedef vector<pip>vip;
// #define mt make_tuple
// typedef tuple<int,int,int> tp;
// typedef vector<tp> vt;
template<typename A,typename B>bool cmin(A &a,const B &b){return a>b?(a=b,true):false;}
template<typename A,typename B>bool cmax(A &a,const B &b){return a<b?(a=b,true):false;}
//template<class C>constexpr int size(const C &c){return (int)c.size();}
//template<class T,size_t N> constexpr int size(const T (&xs)[N])noexcept{return (int)N;}
const double PI=acos(-1);
const double EPS=1e-9;
Def inf = sizeof(Def) == sizeof(long long) ? 1e18+10 : 1e9+10;
// int dx[]={0,1,0,-1,1,1,-1,-1};
// int dy[]={1,0,-1,0,1,-1,1,-1};//RDLU
int dx[]={-1,-1,0,0,1,1};
int dy[]={-1,0,-1,1,0,1};//RDLU
int main(){
	int n;
	cin>>n;
	vi in(n);
	rep(i,n)cin>>in[i];
	vvd dp(n,vd(300000,inf));
	rep(i,300000)dp[0][i]=(double)abs(in[0]-i)/in[0];
	rep(i,n-1)loop(j,1,300000){
		for(int k=j;k<300000;k+=j){
			cmin(dp[i+1][k],max(dp[i][j],(double)abs(in[i+1]-k)/in[i+1]));
		}
	}
	double out=inf;
	rep(i,300000)cmin(out,dp[n-1][i]);
	cout<<shosu(11)<<out<<endl;
}	
	
	
/*
int main(){
	int n,l,t,co=0;
	cin>>n>>l>>t;
	
	vvi in(n,vi(2));
	rep(i,n)rep(j,2)cin>>in[i][j];
	rep(i,n)if(in[i][1]==2)in[i][1]=-1;
	
	vvi g(n,vi(2));
	rep(i,n){
		if(in[0][1]!=in[i][1]){
			ll w=t;
			co+=w/l;
			w%=l;
			ll dis=(l+in[i][0]-in[0][0])%l;
			if(in[0][1]==-1)dis=(l+in[0][0]-in[i][0])%l;
			if(dis<=2*w)co++;
		}
		g[i]={(in[i][0]+t*in[i][1])%l,in[i][1]};
	}
	if(in[0][1]==-1)co=n-1-co%n;
	else co%=n;
	cout<<co<<endl;
	show2d(in);
	show2d(g);
}	
*/







