using System;
public class Program
{
public static void Main()
Console.WriteLine(IsPrimeNumberNaive(5));
Console.WriteLine(IsPrimeNumberOptimized(5));
}
public static bool IsPrimeNumberNaive(int n)
var i = n - 1;
var isPrime = true;
while (i > 1 && isPrime)
isPrime = !(n % i == 0);
i--;
return isPrime;
public static bool IsPrimeNumberOptimized(int n)
var i = 2;
while (i <= Math.Sqrt(n) && isPrime)
i++;