题解

#include<iostream>
using namespace std;
int zhishu(int shu){
	int p = 1;
	for(int i = 2;i < shu;i ++){
		if(shu % i == 0){
			p = 0;
		}
	}
	if(shu == 1){
		p = 0;
	}
	return p;
}

int main(){
	int a,g,k;
	cin >> a;
	for(int i = 3;i < a - 1;i ++){
		g = zhishu(i);
		k = zhishu(i + 2);
		if(g == 1 && k == 1){
			cout << i << " " << i + 2 << endl;
	}
}
	return 0;
}