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)

//eratosurenesu
#include<stdio.h>
#define MAX_V 10000
int prime[MAX_V+1];
int main(){
	int i,k,v;
	for(i=2;i<=MAX_V;i++){
		prime[i]=1;
	}
	for(i=2;i*i<=MAX_V;i++){
		if(prime[i]){
			for(k=2*i;k<=MAX_V;k+=i){
				prime[k]=0;
			}
		}
	}
	while(scanf("%d",&v)!=0){
		for(i=v;i>=2;i--){
			if(prime[i]==1 && prime[i-2]==1){
				printf("%d %d\n",i-2,i);
				break;
			}
		}
	}
	return 0;
}