using System;
  public class PrimeNumberExample
   {
     public static void Main(string[] args)
      {
          int n, i, m=0, flag=0;  
          Console.Write("Enter the Number to check Prime: ");  
          n = int.Parse(Console.ReadLine());
          m=n/2;  
          for(i = 2; i <= m; i++)  
          {  
           if(n % i == 0)  
            {  
             Console.Write("Number is not Prime.");  
             flag=1;  
             break;  
            }  
          }  
          if (flag==0)  
           Console.Write("Number is Prime.");     
     }
   }

Enter the Number to check Prime: 17  
Number is Prime.   

Enter the Number to check Prime: 57  
Number is not Prime.