#include <cstdio>
#include <vector>
#include <queue>
#include <stack>
#include <list>
#include <set>
#include <algorithm>
#include <utility>
#include <string>
#include <functional>
#include <sstream>
#include <fstream>
#include <iostream>
using namespace std;
#define FOR(i,a,b) for (i=a;i<=b;i++)
#define fori(it,v) for (it=(v).begin();it!=(v).end();it++)
#define pb push_back
#define mp make_pair
#define fs first
#define ss second
#define all(c) c.begin(),c.end()
#define pf push_front
#define popb pop_back
#define popf pop_front
int ver(int y)
{
	long long rez=-(1<<35);
	FOR(i,1,n)
	{
		
	}
	if (rez>=0)
		return 1;
	return 0;
}
int main()
{
	FILE *in,*out;
	in=fopen("secv3.in"."r");
	out=fopen("secv3.out","w");
	fscanf(in,"%lld%lld%lld",&n,&L,&u);
	FOR(i,1,n)
	{
		fscanf(in,"%lld",&a[i]);
		a[i]*=1000;
	}
	FOR(i,1,n)
		fscanf(in,"%lld",&b[i]);
		
	int rez=0;
	for (i=1<<35;i;i>>=1)
	{
		rez+=i;
		if (ver(rez))
			rez-=i;
	}
	rez++;
	fprintf(out,"%lld.%lld\n",rez/1000,rez%1000);
	fclose(in);
	fclose(out);
	return 0;
}