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"
//#include "time.h"
//?????§??????????´???°?????????????????????
// 5<= n <= 10000
//p1=?°????????´???°p2=??§???????´???°

int isprime(int n) {
    for(int i = 2; i < n; i++) {   //??????????§????????????¨??§??¶??°??§??????????´???°??¨??????
        if(n % i == 0)return 0;    //????????????????????§?´???°??§?????????
    }
    return 1;
}


int main(){
    int i,n,p1,q1;
    //    clock_t start, now;//??£?¨?
    while(1){
        scanf("%d",&n);
        //        start = clock(); // ????§???????
        if(n == 0)break;
        for(i = n;3 <= i;i--){
            if (isprime(i) == 1 && isprime(i - 2) == 1) break;
        }
        p1 = i-2;
        q1 = i;
        //        now = clock(); // ????????????
        //        printf("%f\n", (double)(now - start) / CLOCKS_PER_SEC);//??¬???
        printf("%d %d\n",p1,q1);
    }
}