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: Accepted)

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


public class Main {

	boolean[] sieve;
	Scanner sc;
	
	int ni(){
		return sc.nextInt();
	}
	
	void makeSieve(int max){
		sieve=new boolean[max+1];
		Arrays.fill(sieve,true);
		sieve[0]=false;
		for(int i=2;i<=max;++i){
			if(sieve[i-1]){
				for(int j=i*2;j<=max;j+=i){
					sieve[j-1]=false;
				}
			}
		}
	}
	
	void solve(int n){
		for(int i=n;i>4;--i){
			if(sieve[i-1]&&sieve[i-3]){
				System.out.println((i-2)+" "+i);
				break;
			}
		}
	}
	
	void io(){
		sc=new Scanner(System.in);
		int n;
		makeSieve(10000);
		while((n=ni())!=0){
			solve(n);
		}
		sc.close();
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		new Main().io();
	}

}