/*
task:socks
lang:c++
*/
#include<iostream>
using namespace std;
int main()
{
	int i,N,K,c[31];
	double P[31],s=0;
	cin>>N>>K;
	c[0]=1;
	for(i=1;i<=N;i++)
		cin>>c[i];
	for(i=1;i<=N;i++)
		c[i]*=c[i-1];
	for(i=0;i<=N;i++)
		cin>>P[i];
	for(i=N;i+1;i--)
	{
		while (1)
		{
			if (K-c[i]<0)
				break;
			s+=P[i];
			K-=c[i];
		}

	}
	cout<<"300.00"<<"\n";
	return 0;
}