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: Time Limit Exceeded)

import java.util.Arrays;
import java.util.Scanner;

public class Main
{
	public static void main(String arg[])
	{
		Scanner sc = new Scanner(System.in);

		while(sc.hasNext())
		{
			int n = sc.nextInt();
			if(n==0)
				return;
			int ans =0;
			boolean a[] = new boolean[n+1];
			Arrays.fill(a, true);
			a[0]=a[1]=false;

			for(int i=0;i<=n; i++)
			{
				if(!a[i]) //falseだったら
					continue;
				for(int j=i+i; j<=n; j+=i)
				{
					a[j] = false;
				}

			}
			int x=0;
			int y=0;
			boolean flag=false;
			for(int i =n; i>=0; i--)
			{
				if(a[i])
					x =i;
				for(int j=i-1; j>=0; j--)
				{
					if(a[j])
					{
						y=j;
						if(x-y==2)
						{
							System.out.println(y+" "+x);
							flag = true;
							break;
						}
					}
				}	
				if(flag)
					break;
			}
		}
	}

}