Description：

Solution：

Code：

#include<algorithm>

#include<iostream>

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<cctype>

#include<cstring>

using namespace std;

inline int rd()

{

	register int res = 0,f = 1;register char c = getchar();

	while(!isdigit(c)){if(c == '-')f = -1;c = getchar();}

	while(isdigit(c))res = (res << 1) + (res << 3) + c - '0',c = getchar();

	return res * f;

}

int n;

#define MAXN 2010

double p[MAXN],q[MAXN];

int a,b;

typedef long long ll;

#define F 1e12

struct state

{

	double val;

	int cnta,cntb;

};

#define eps 1e-9

bool equal(double a,double b){return fabs(a - b) <= eps;}

bool operator < (state a,state b){return (a.val == b.val ? (a.cntb == b.cntb ? a.cnta > b.cnta : a.cntb > b.cntb) : a.val < b.val);}

state operator + (state a,state b){return (state){a.val + b.val,a.cnta + b.cnta,a.cntb + b.cntb};}

state f[MAXN];

state calc2(double ca,double cb)

{

	for(int i = 1;i <= n;++i)

	{

		f[i].val = f[i].cnta = f[i].cntb = 0;

		f[i] = max(f[i],f[i - 1]);

		f[i] = max(f[i],f[i - 1] + (state){ca + p[i],1,0});

		f[i] = max(f[i],f[i - 1] + (state){cb + q[i],0,1});

		f[i] = max(f[i],f[i - 1] + (state){ca + cb + 1 - (1 - p[i]) * (1 - q[i]),1,1});

	}//cout << ca << " " << cb << " " << f[n].val << " " << f[n].cnta << " " << f[n].cntb << endl;

	return f[n];

}

state calc1(double ca)

{

	double l = -1,r = 1,mid;

	for(int i = 1;i <= 200;++i)

	{

		mid = 0.5 * (l + r);

		if(calc2(ca,mid).cntb <= b)l = mid;

		else r = mid;

	}

	state res = calc2(ca,l);

	return (state){res.val - b * l,res.cnta,res.cntb};

}

int main()

{

	scanf("%d%d%d",&n,&a,&b);

	for(int i = 1;i <= n;++i)scanf("%lf",&p[i]);

	for(int i = 1;i <= n;++i)scanf("%lf",&q[i]);

	double l = -1,r = 1,mid;

	for(int i = 1;i <= 200;++i)

	{

		mid = 0.5 * (l + r);

		state res = calc1(mid);

		if(res.cnta <= a)l = mid;

		else r = mid;

	}

	printf("%.10lf\n",calc1(l).val - a * l);

	return 0;

}