Problem:
Twin Prime

Prime numbers are widely applied for cryptographic and communication technology.
A twin prime is a prime number that differs from another prime number by 2.
For example, (5, 7) and (11, 13) are twin prime pairs.

In this problem, we call the greater number of a twin prime "size of the twin prime."

Your task is to create a program which reads an integer n and prints a twin prime which has the maximum size among twin primes less than or equals to n

You may assume that 5 ≤ n ≤ 10000.

Input

The input is a sequence of datasets. The end of the input is indicated by a line containing one zero. Each dataset is formatted as follows:

n (integer)

Output

For each dataset, print the twin prime p and q (p < q). p and q should be separated by a single space.

Sample Input

12
100
200
300
0

Output for the Sample Input

5 7
71 73
197 199
281 283

Solution in Ruby (judge verdict: Accepted)

N = 10007

sieve = [*0..N]
2.upto(Math.sqrt(N).to_i) do |i|
  next if sieve[i].zero?
  2.upto(N / i) {|j| sieve[i * j] = 0}
end
sieve = sieve[2..-1].reject {|x| x.zero?}

until (n = $<.gets.to_i).zero?
  idx = sieve.index {|i| i > n}
  i = 1
  i += 1 until sieve[idx - i] - sieve[idx - i - 1] == 2
  puts "#{sieve[idx - i - 1]} #{sieve[idx - i]}"
end