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Time Limit: 1.0 Seconds Memory Limit: 65536K

Total Runs: 2221 Accepted Runs: 780

This conjecture has not been proved nor refused yet. No one is sure whether this conjecture actually holds. However, one can find such a pair of prime numbers, if any, for a given even number. The problem here is to write a program that reports the number of all the pairs of prime numbers satisfying the condition in the conjecture for a given even number.

A sequence of even numbers is given as input. Corresponding to each
number, the program should output the number of pairs mentioned above.
Notice that we are interested in the number of essentially different pairs
and therefore you should not count *(p _{1} , p_{2})*
and

**Input**

An integer is given in each input line. You may assume that each integer
is even, and is greater than or equal to 4 and less than 2^{15}.
The end of the input is indicated by a number 0.

**Output**

Each output line should contain an integer number. No other characters should appear in the output.

**Sample Input**

6 10 12 0

1 2 1

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