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: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	static final int N = 10000;

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = "";

		boolean[][] primes = new boolean[N + 1][2];

		for (int i = 2; i < N / 2 + 1; i++) {
			if (!primes[i][0]) {
				for (int j = i * 2; j < N + 1; ) {
					primes[j][0] = true;
					j += i;
				}
				if (!primes[i - 2][0]) {
					primes[i][1] = true;
				}
			}
		}

		while ((line = br.readLine()) != null && !line.isEmpty()) {
			int n = Integer.parseInt(line);
			if (n == 0) {
				break;
			}
			for (int i = n; i > 4; i--) {
				if (primes[i][1]) {
					System.out.println(i - 2 + " " + i);
					break;
				}
			}
		}
	}
}