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: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;
int main()
{
    bool prime[10005];
    memset(prime,0,sizeof(prime));
    for(int i=2;i<sqrt(10005);i++){
        if(!prime[i])for(int j=i*2;j<10005;j+=i)prime[j]=1;
    }
    int num[210],co=0;
    for(int i=3;i<10001;i++){
        if(!prime[i]&&!prime[i+2]){
            num[co]=i;
            co++;
        }
    }
    int n;
    while(cin>>n,n){
        if(num[co-1]<n)cout<<num[co-1]<<" "<<num[co-1]+2<<endl;
        else{
            for(int i=0;i<co;i++){
                if(num[i]>=n&&num[i-1]+2<=n){
                    cout<<num[i-1]<<" "<<num[i-1]+2<<endl;
                    break;
                }
                else if(num[i]>n){
                    cout<<num[i-2]<<" "<<num[i-2]+2<<endl;
                    break;
                }
            }
        }
    }
}