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 C (judge verdict: Time Limit Exceeded)

#include<stdio.h>
int n,cnt;
int i,j,p1,q1;
int ityan;
int main(void){
	
	scanf("%d",&n);
	while(n!=0){
		p1=0;
		q1=0;
		for(i=5;i<=n;i++){
			cnt=1;
			for(j=1;j<=9;j++){
				if(j!=1){
					if(i!=j){
						if(i%j==0){
							cnt++;
						}
					}
				}
			}
			if(n>i+2){
				if(cnt==1){
					cnt=1;
					ityan=i+2;
					for(j=1;j<=9;j++){
						if(j!=1){
							if(ityan!=j){
								if(ityan%j==0){
									cnt++;
								}
							}
						}
					}
					if(cnt==1){
						p1=i;
						q1=ityan;
					}
				}
			}
		}
		printf("%d %d\n",p1,q1);
		scanf("%d",&n);
	}
	return 0;
}