public static void Main()
Console.WriteLine("Enter a positive integer");
n = long.Parse(Console.ReadLine());
{ Console.WriteLine(n + " is not prime");}
{ Console.WriteLine(n + " is prime");}
{ Console.WriteLine(n + " =2*" + n/2);}
for (int d = 3; d <= n/2; d += 2)
Console.WriteLine (n + " is divisible by" +d+ " so it is not prime");
Console.WriteLine(n + " is prime");