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 isprime(int n){
 int i;
 for(int i= 2; i * i<=n; i++){
  if(n % i== 0) return 0;
 }
 return 1; 
}


int main(){
 int max1 = 0, max2 = 0, i, n;
 while(1){
  scanf("%d", &n);
  if(n == 0) break;
  for(i = 2; i + 2 < n; i++){
   if(isprime(i) == 1 && isprime(i + 2) == 1){
    max1 = i;
    max2 = i + 2;
   }
  }
  printf("%d %d\n", max1, max2);
 }
 return 0;
}