#include <iostream>
using namespace std;

int CheckPrime(int n)
{
	int s = 0;
	for (int i = 1; i <= n; i++)
	{
		if (n % i == 0)
			s++;
	}
	if (s == 2)
		return 1;
	return 0;
}
void main()
{
	int n;
	do {
		cout << "Nhap so n:";
		cin >> n;
	} while (n <= 0);
	if (CheckPrime(n)&&n!=1)
		cout << "Day la so nguyen to";
	else cout << "Day khong phai la so nguyen to";
}