#include<iostream>
#include<random>
#include<vector>
#include<algorithm>
#include<iomanip>
using namespace std;
int N;
int PA,PB;
main()
{
	cin>>N;
	double pa,pb;
	cin>>pa>>pb;
	PA=pa*1e6;
	PB=pb*1e6;
	vector<int>A(N),B(N);
	for(int&a:A)cin>>a;
	for(int&b:B)cin>>b;
	sort(A.begin(),A.end());
	sort(B.begin(),B.end());
	mt19937 rng(114514);
	int wc=0;
	const int TM=1e6;
	for(int c=0;c<TM;c++)
	{
		vector<int>a=A,b=B;
		int as=0,bs=0;
		for(int i=0;i<N;i++)
		{
			if(i+1==N)
			{
				if(a[0]<b[0])bs+=a[0]+b[0];
				else as+=a[0]+b[0];
			}
			else
			{
				int A,B;
				int at=rng()%TM;
				if(at<PA)
				{
					A=a[0];
					a.erase(a.begin());
				}
				else
				{
					int id=rng()%(N-i-1)+1;
					A=a[id];
					a.erase(a.begin()+id);
				}
				int bt=rng()%TM;
				if(bt<PB)
				{
					B=b[0];
					b.erase(b.begin());
				}
				else
				{
					int id=rng()%(N-i-1)+1;
					B=b[id];
					b.erase(b.begin()+id);
				}
				if(A<B)bs+=A+B;
				else as+=A+B;
			}
		}
		if(as>bs)wc++;
	}
	cout<<fixed<<setprecision(16)<<wc/(double)TM<<endl;
}