1290. Goldbach's Conjecture

单点时限: 2.0 sec

内存限制: 256 MB

In 1742, Christian Goldbach, a German amateur mathematician, sent a letter to Leonhard Euler in which he made the following conjecture:

Every even number greater than 4 can be

written as the sum of two odd prime numbers.

For example:

8 = 3 + 5. Both 3 and 5 are odd prime numbers.

20 = 3 + 17 = 7 + 13.

42 = 5 + 37 = 11 + 31 = 13 + 29 = 19 + 23.

Today it is still unproven whether the conjecture is right. (Oh wait, I have the proof of course, but it is too long to write it on the margin of this page.)

Anyway, your task is now to verify Goldbach’s conjecture for all even numbers less than a million.

输入格式

The input will contain one or more test cases.

Each test case consists of one even integer n with 6 <= n < 1000000.

Input will be terminated by a value of 0 for n.

输出格式

For each test case, print one line of the form n = a + b, where a and b are odd primes. Numbers and operators should be separated by exactly one blank like in the sample output below. If there is more than one pair of odd primes adding up to n, choose the pair where the difference b - a is maximized. If there is no such pair, print a line saying “Goldbach’s conjecture is wrong.”

样例

Input
8
20
42
0
Output
8 = 3 + 5
20 = 3 + 17
42 = 5 + 37

32 人解决,52 人已尝试。

40 份提交通过,共有 127 份提交。

5.0 EMB 奖励。

创建: 13 年,8 月前.

修改: 3 年,7 月前.

最后提交: 4 月,3 周前.

来源: Ulm Local 1998

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