题目描述 Grading hundreds of thousands of Graduate Entrance Exams is a hard work. It is even harder to design a process to make the results as fair as possible. One way is to assign each exam problem to $3$ independent experts. If they do not agree to each other, a judge is invited to make the final decision. Now you are asked to write a program to help this process. For each problem, there is a full-mark $P$ and a tolerance $T$ $(<P)$ given. The grading rules are: A problem will first be assigned to $2$ experts, to obtain $G1$ and $G2$. If the difference is within the tolerance, that is, if $ G1 - G2 \leq T$, this problem's grade will be the average of $G1$ and $G2$. If the difference exceeds $T$, the $3$rd expert will give $G3$. If $G3$ is within the tolerance with either $G1$ or $G2$, but NOT both, then this problem's grade will be the average of $G3$ and the closest grade. If $G3$ is within the tolerance with both $G1$ and $G2$, then this problem's grade will be the maximum of the three grades. If $G3$ is within the tolerance with neither $G1$ nor $G2$, a judge will give the final grade $GJ$. 输入格式 Each input file may contain more than one test case. Each case occupies a line containing six positive integers: $P$, $T$, $G1$, $G2$, $G3$, and $GJ$, as described in the problem. It is guaranteed that all the grades are valid, that is, in the interval $[0, P]$. 输出格式 For each test case you should output the final grade of the problem in a line. The answer must be accurate to $1$ decimal place. 输入样例 20 2 15 13 10 18 输出样例 14.0