#include<bits/stdc++.h> using namespace std; // 判断一个数是否为质数 bool h(int m) { if (m <= 1) return false; if (m == 2) return true; if (m % 2 == 0) return false; for (int i = 3; i <= sqrt(m); i += 2) { if (m % i == 0) return false; } return true; } int main() { int n; cin >> n; for (int i = 2; i <= n - 2; i++) { if (h(i) && h(i + 2)) { cout << i << " " << i + 2 << endl; } } return 0; } /************************************************************** Problem: 1139 User: wangyiyang Language: C++ Result: Accepted Time:12 ms Memory:2072 kb ****************************************************************/