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.*;class Main{public static void main(String[]z){Scanner s=new Scanner(System.in);int[]p=new int[30];int i=0,e=2;for(;i<30;p[i++]=e++)for(;f(p,e)<1;e++);for(;(e=s.nextInt())>0;System.out.println(e-2+" "+e))for(;e>4;--e)if(f(p,e)+f(p,e-2)>1)break;}static int f(int[]p,int n){for(int e:p)if(e>0&&n!=e&&n%e<1)return 0;return 1;}}