#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 2000000000

unsigned long xor128() {
	static unsigned long x=123456789, y=362436069, z=521288629, w=88675123;
	unsigned long t=(x^(x<<11));
	x=y; y=z; z=w;
	return (w=(w^(w>>19))^(t^(t>>8)));
}

int main(){	
	
	int N;
	cin>>N;
	int Pa,Pb;
	{
		double t;
		cin>>t;
		t *= 1000;
		Pa = round(t);
	}
	{
		double t;
		cin>>t;
		t *= 1000;
		Pb = round(t);
	}
	vector<int> a(N),b(N);
	rep(i,N){
		cin>>a[i];
	}
	rep(i,N){
		cin>>b[i];
	}
	sort(a.begin(),a.end());
	sort(b.begin(),b.end());
	double ans = 0.0;
	rep(i,1000000){
		
		auto aa = a,bb = b;
		int Sa = 0,Sb = 0;
		rep(j,N){
			int x,y;
			if(j==N-1||xor128()%1000<Pa)x = 0;
			else x = xor128()%(N-1-j)+1;
			if(j==N-1||xor128()%1000<Pb)y = 0;
			else y = xor128()%(N-1-j)+1;
			if(aa[x]>bb[y]){
				Sa += aa[x]+bb[y];
			}
			else{
				Sb += aa[x]+bb[y];
			}
			aa.erase(aa.begin()+x);
			bb.erase(bb.begin()+y);
			
		}
		if(Sa>Sb){
			ans += 1.0 / 1000000.0;
		}
	}
	
	cout<<fixed<<setprecision(10)<<ans<<endl;
	
	return 0;
	
}