Grading

    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| ≤ T, this problem's grade will be the average of G1 and G2.     • If the difference exceeds T, the 3rd 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.

    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].

    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.

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