C++ :

#include<iostream>
#include<cmath>
using namespace std;
int b[1001];
int ss(int );
int main()
{
   int n;
   cin>>n;
   for(int i=1;i<=n-2;++i)
   {
		if(ss(i)==0&&ss(i+2)==0)
			cout<<i<<" "<<i+2<<endl;
   }
   return 0;
}
int ss(int a)
{
	if(a==1||a==0||a<0)return 1;
	else
	{
		int x=2;
    int c=floor(sqrt(a));
	while(x<=c&&a%x!=0)
		++x;
	if(x>c)return 0;
	else return 1;
	}
}