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 JAVA (judge verdict: Memory Limit Exceeded)

import java.util.*;
import java.math.*;

class Main {
  public static void main (String[] args) {
    Scanner scanner = new Scanner(System.in);
    while (scanner.hasNext()) {
      String line = scanner.nextLine();
      if (line.equals("0")) {
        break;
      }
      int n = Integer.parseInt(line);
      int p1 = 0;
      int p2 = 0;
      for (int ii = n; ii > 1; ii--) {
        BigInteger a = new BigInteger(String.format("%d", ii));
        if (!a.isProbablePrime(1)) {
          continue;
        }
        p2 = p1;
        p1 = ii;
        if (p2 - p1 == 2) {
          System.out.println(p2 + " " + p1);
          break;
        }
      }
    }
  }
}