#include <iostream>
#include <cmath>
#include <time.h>
#include <vector>

using namespace std;

bool isPrime(int num)
{
    if (num == 2) {
        return true;
    }
    if (num <= 1 || num % 2 == 0) {
        return false;
    }

    double sqrt_num = sqrt(double(num));
    for (int div = 3; div <= sqrt_num; div +=2)
    {
        if (num % div == 0) {
            return false;
        }
    }
    return true;
}


int main()
{
    int N = 10'000'000;
    clock_t start, end;
    std::vector<int> list(N);
    list.clear();
    start = clock();

    for (int i = 0; i < N; i++) {
        bool prime = isPrime(i);
        if (prime) {
            list.push_back(i);
        }
    }

    end = clock();
    cout << endl << endl << (end - start) / ((double) CLOCKS_PER_SEC);
    cout << " sec \n";
    return 0;
}