#include<bits/stdc++.h>
#define FILE "read"
#define MAXN 100100
#define INF 1e9
using namespace std;
const int chty=1000000;//常数
struct node{int y,next,v,w;}e[MAXN<<1];
int n,A,B,S,T,IdA,IdB,IdC,cnt,ans,len(1),Id[MAXN],Link[MAXN],dis[MAXN],flow[MAXN],vis[MAXN],LE[MAXN],LN[MAXN];
double P[MAXN],u[MAXN];
queue<int>q;
inline int read(){
	int x=0,f=1;  char ch=getchar();
	while(ch>'9'||ch<'0')  {if(ch=='-')  f=-1;  ch=getchar();}
	while(ch>='0'&&ch<='9')  {x=x*10+ch-'0';  ch=getchar();}
	return x*f;
}
void insert(int x,int y,int v,int w){
	e[++len].next=Link[x];Link[x]=len;e[len].y=y;e[len].v=v;e[len].w=w;
	e[++len].next=Link[y];Link[y]=len;e[len].y=x;e[len].v=0;e[len].w=-w;
}
bool spfa(){
	for(int i=1;i<=cnt;++i) vis[i]=0;
	for(int i=1;i<=cnt;++i) dis[i]=INF;
	q.push(S);  vis[S]=1;  dis[S]=0;  flow[S]=INF;
	while(!q.empty()){
		int x=q.front();  q.pop();  vis[x]=0;
		for(int i=Link[x];i;i=e[i].next)if(dis[x]+e[i].w<dis[e[i].y]&&e[i].v){
			dis[e[i].y]=dis[x]+e[i].w;
			flow[e[i].y]=min(flow[x],e[i].v);
			LN[e[i].y]=x;  LE[e[i].y]=i;
			if(!vis[e[i].y])  vis[e[i].y]=1,q.push(e[i].y);
		}
	}
	if(dis[T]==INF) return 0;
	ans-=flow[T]*dis[T];
	for(int i=T;i!=S;i=LN[i]) e[LE[i]].v-=flow[T],e[LE[i]^1].v+=flow[T];
	return 1;
}
int main(){
	//freopen(FILE".in","r",stdin);
	//freopen(FILE".out","w",stdout);
	n=read();  A=read();  B=read();
	S=++cnt;  T=++cnt;  IdA=++cnt;  IdB=++cnt;  IdC=++cnt;
	for(int i=1;i<=n;++i)  Id[i]=++cnt;
	for(int i=1;i<=n;++i)  scanf("%lf",&P[i]);
	for(int i=1;i<=n;++i)  scanf("%lf",&u[i]);
	insert(S,IdA,A,0);  insert(S,IdB,B,0);
	for(int i=1;i<=n;++i){
		insert(IdA,Id[i],1,-P[i]*chty);
		insert(IdB,Id[i],1,-u[i]*chty);
		insert(Id[i],IdC,1,0);
		insert(Id[i],IdC,1,P[i]*u[i]*chty);
	}
	insert(IdC,T,INF,0);
	while(spfa());
	printf("%.18lf\n",(double)ans/chty);
	return 0;
}