bool isPrime(int x = 0)
{
/* Without extra 'count' variable */
//! corner case: 0 and 1 aren't prime numbers
if (x == 0 || x == 1)
return 0;
for (int i = 2; i <= x / 2; i++)
{
if (x > 2 && x % i == 0)
return 0;
}
return 1;
}