#include<algorithm>
#include<cstdio>
namespace IO{
	const int ARR_SIZE=1<<20;
	#define gc() ((IO::si!=IO::ti||(IO::ti=(IO::si=IO::input)+fread(IO::input,1,IO::ARR_SIZE,stdin))),IO::si!=IO::ti?*(IO::si++):EOF)
	char input[ARR_SIZE],*si=input,*ti=input;
	template<typename T>
	void read(T&num){
		int ch=gc();
		num=0;
		while(ch<48||ch>57)ch=gc();
		while(ch>=48&&ch<=57)num=(num<<3)+(num<<1)+(ch^48),ch=gc();
	}
}
using IO::read;
typedef double real;
const int maxn=10000000;
int n,L,V,v[maxn+1];
real K,B,pre,l,r,ans=1e308;
int main(){
	read(n),read(L),read(V);
	for(int i=1;i<=n;i++)read(v[i]);
	for(int i=1;i<=n;i++){
		K+=1-2.0*v[i]/(v[i]+V);
		B+=2.0*L/(v[i]+V);
	}
	for(int i=n;i>=1;i--){
		r=(real)L/v[i];
		if(K>=0)ans=std::min(ans,K*l+B+pre);
		else ans=std::min(ans,K*r+B+pre);
		K-=1-2.0*v[i]/(v[i]+V);
		B-=2.0*L/(v[i]+V);
		pre+=r,l=r;
	}
	ans=std::min(ans,pre);
	printf("%.10lf\n",ans/n);
	return 0;
}