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: Runtime Error)

#include <stdio.h>
#include <math.h>

int prime[16384];

int sosu ( int n ) {
	int i , lim = (int)(sqrt(n));
	if ( n < 2 ) return 0;
	for ( i = 2; i <= lim; i++ ) {
		if ( n % i == 0 ) return 0;
	}
	return n;
}

void tmp(void) {
	int i , j = 0;
	for ( i = 0; i < 10000; i++ ) {
		if ( sosu(i) ) {
			prime[j] = sosu(i);
			j++;
		}
	}
	return;
}

int main (void) {
	int n , i , j;
	tmp();
	
	while (1) {
		int twin = 0;
		scanf("%d",&n);
		if ( n == 0 ) break;
		
		for ( i = 0; prime[i+1] < n; i ++ ) {
			if ( prime[i+1] - prime[i] == 2 ) {
				twin = prime[i];
			}
		}
		printf("%d %d\n",twin,twin+2);
	}
	return 0;
}