Goldbach's Conjecture

Time Limit: 2 Seconds
Memory Limit: 65536 KB

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.

**Input**

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.

**Output**

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."

**Sample Input**

8

20

42

0

**Sample Output**

8 = 3 + 5

20 = 3 + 17

42 = 5 + 37

Source:

**University of Ulm Local Contest 1998**
Submit
Status