//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;
}