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[UVA][循環] 12464 - Professor Lazy, Ph.D.

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Problem D. Professor Lazy, Ph.D.

Professors are very motivated when they have to travel abroad for a conference (of course, if fees are paid by the university), but they don’t have the same attitude when the moment to grade exams arrives.

Professor Lazy, Ph.D., has a particular way to grade exams (and very unfair, by the way). He puts all his exams in a box and then starts getting them out one by one in a totally random fashion. He assigns grade α to the first exam that he gets out of the box, and grade β to the second exam that he gets out of the box. From that point on, he assigns a grade to each of the exams based on the grades of the previous two exams. What he does is that he takes the grade of the immediately previous exam, adds 1 and divides by the grade of the exam before the previous one.

For example, let’s imagine that α = 2 and β = 3. This is what happens:

  • The first exam gets α = 2.
  • The second exam gets β = 3.
  • The previous two grades are α and β, so the third exam gets (1 + β)
    -------
       α = (1 + 3)
    -------
       2 = 2.
  • The previous two grades are β and (1+-β)-
      α, so the fourth exam gets 1-+-(1+αβ)
        β = 1+-2-
      3 = 1.
  • The procedure continues until he’s done with all exams.

More formally, we can define the grade Qn of the nth exam with a recurrence like this:

Qn = (
    || α          if n = 0,
    |{
      β          if n = 1,
    |||( 1-+-Qn--1
        Qn -2    if n ≥ 2.

Even this simple procedure is a lot of work for Professor Lazy, Ph.D., so he asks you to write a program to do it for him. He wants to spend all day long drinking coffee in the cafeteria with other professors. Given α, β and n find the value of Qn.

Note that the grades do not necessarily lie inside a fixed range. They are just arbitrary integers.

Input

The input contains several test cases (at most 1000). Each test case is described by three integer numbers α, β and n on a single line (1 α, β 109 and 0 n 1015).

The last line of the input contains three zeros and should not be processed.

Output

For each test case, write the value of Qn in a single line. The input will be such that the value of Qn is always an integer. Furthermore, Qi will never be zero for 0 i n (in other words, division by zero will never arise when evaluating the recurrence).

Sample input and output

standard input
standard output


1 1 0

1 2 1

5 9 2

2 3 3

7 4 4

2109 650790 344341899059516

45861686 57 594261603792314

2309734 21045930 808597262407955

0 0 0

1

2

2

1

2

650790

804591

2309734

台長: Morris
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