#include using namespace std; int main() { int n; cin >> n; for (int i = 6; i <= n; i+=6) { int firstNumToCheck = i - 1, secondNumToCheck = i + 1; double temp = sqrt(firstNumToCheck); bool isFirstNumPrime = true; for (int j = 2; j <= temp; j++) { if (firstNumToCheck % j == 0) { isFirstNumPrime = false; break; } } if (!isFirstNumPrime) continue; double temp2 = sqrt(secondNumToCheck); bool isSecondNumPrime = true; for (int j = 2; j <= temp2; j++) { if (secondNumToCheck % j == 0) { isSecondNumPrime = false; break; } } if (isSecondNumPrime) cout << firstNumToCheck << " " << secondNumToCheck << endl; } }