//不是说C语言就是C++的子集么，为毛printf在九度OJ上不能通过编译，abs还不支持参数为整型的abs()重载

//C++比较正确的做法是#include<cmath.h>，cout的格式输出需要用到#include<iomanip>库函数，具体为：cout<<fixed<<setprecision(1)<<score<<endl;结果保留一位小数

#include<iostream>

#include<iomanip>

#include<cmath>

using namespace std;

int maxscore(int ,int ,int);

int main()

{

	double p,t,g1,g2,g3,gj;

	while(cin>>p>>t>>g1>>g2>>g3>>gj)

	{

		double score;

		if(g1<=p&&g2<=p&&t<p)

		{

			if(abs(g1-g2)<=t)

			{

				score=(g1+g2)/2.0;

			}else if(abs(g1-g3)<=t&&abs(g3-g2)<=t)

			{

				score=maxscore(g1,g2,g3);

			}else if(abs(g1-g3)<=t||abs(g3-g2)<=t)

			{

				if(abs(g1-g3)<abs(g2-g3))

				{

					score=(g1+g3)/2.0;

				}else

				{

					score=(g2+g3)/2.0;

				}

			}

			else

			{

				score=gj;

			}

		}

		cout<<fixed<<setprecision(1)<<score<<endl;

	}

	return 0;

}

int maxscore(int g1,int g2 ,int g3)

{

	double score;

	if(g1>g2)

	{

		if(g1>g3)

			score=g1;

		else

			score=g3;

	}else

	{

		if(g2>g3)

			score=g2;

		else

			score=g3;

	}

	return score;

}