#include<bits/stdc++.h>
using namespace std;

int main(){
    int n, v, pa, pb;
    scanf("%d 0.%d 0.%d", &n, &pa, &pb);
    set<int> Sa, Sb;
    for(int i = 0; i < n; i++){
        cin >> v;
        Sa.insert(v);
    }
    for(int i = 0; i < n; i++){
        cin >> v;
        Sb.insert(v);
    }
    auto select = [&](set<int> S, int p){
        int v;
        if(S.size() == 1 || rand() % 1000 < p)v = *S.begin();
        else{
            int cnt = rand() % (S.size() - 1) + 1;
            auto it = S.begin();
            for(int i = 0; i < cnt; i++)it++;
            v = *it;
        }
        return v;
    };
    auto f = [&](set<int> A, set<int> B){
        int va, vb, as = 0, bs = 0;
        for(int i = 0; i < n; i++){
            va = select(A, pa);
            vb = select(B, pb);
            A.erase(va), B.erase(vb);
            if(va > vb)as += va + vb;
            else bs += va + vb;
        }
        return (as > bs);
    };
    int cnt = 0, m = 100000;
    for(int i = 0; i < m; i++){
        cnt += f(Sa, Sb);
    }
    printf("%.15lf\n", double(cnt) / m);
}