Time Limit: 2000/1000 MS (Java/Others)

Memory Limit: 32768/32768 K (Java/Others)

Take any four positive integers: a, b, c, d. Form four more, like this:

|a-b| |b-c| |c-d| |d-a|

That is, take the absolute value of the differences of a with b, b with c, c with d, and d with a. (Note that a zero could crop up, but they’ll all still be non-negative.) Then, do it again with these four new numbers. And then again. And again. Eventually, all four integers will be the same. For example, start with 1,3,5,9:

1 3 5 9

2 2 4 8 (1)

0 2 4 6 (2)

2 2 2 6 (3)

0 0 4 4 (4)

0 4 0 4 (5)

4 4 4 4 (6)

In this case, the sequence converged in 6 steps. It turns out that in all cases, the sequence converges very quickly. In fact, it can be shown that if all four integers are less than 2^n, then it will take no more than 3*n steps to converge!

Given a, b, c and d, figure out just how quickly the sequence converges.

That is, take the absolute value of the differences of a with b, b with c, c with d, and d with a. (Note that a zero could crop up, but they’ll all still be non-negative.) Then, do it again with these four new numbers. And then again. And again. Eventually, all four integers will be the same. For example, start with 1,3,5,9:

1 3 5 9

2 2 4 8 (1)

0 2 4 6 (2)

2 2 2 6 (3)

0 0 4 4 (4)

0 4 0 4 (5)

4 4 4 4 (6)

In this case, the sequence converged in 6 steps. It turns out that in all cases, the sequence converges very quickly. In fact, it can be shown that if all four integers are less than 2^n, then it will take no more than 3*n steps to converge!

Given a, b, c and d, figure out just how quickly the sequence converges.

There will be several test cases in the input. Each test case consists of four positive integers on a single line (1 ≤ a,b,c,d ≤ 2,000,000,000), with single spaces for separation. The input will end with a line with four 0s.

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