#include <iostream>

using namespace std;

// 0 - NOT a prime number (0 or 1)
// 1 - IS a prime number
// any other divider - IS NOT a prime number

int prime_number(unsigned long long n)
{
    if(n == 0 || n == 1)
        return 0;
    for(unsigned long long i = 2; i * i <= n; ++i)
        if(n % i == 0)
            return i;
    return 1;
}

int main()
{
    cout << "Please enter a number: ";
    unsigned long long number;
    cin >> number;

    int result = prime_number(number);

    if(result == 0)
        cout << number << " is not a prime number\n";
    else if(result == 1)
        cout << number << " is a prime number\n";
    else
        cout << number << " is not a prime number, because it is divided by " <<  result << endl;
    return 0;
}