using System;  

  public class Example  

   {  

     public static void Main(string[] args)  

      {  

          int n, i, m=0, flag=0; 

         int e;

         int a;

         Console.Write("Enter the Number to check Prime: ");    

          e = int.Parse(Console.ReadLine()); 

         switch(e)

         {

             case 1:

                 {

          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."); 

                 }

                 break;

             case 2:

                 {

                 m= 0;

                 flag= 1;

                     Console.Write("Enter the number of elements: ");    

         n = int.Parse(Console.ReadLine());  

         Console.Write(m+" "+flag+" "); //printing 0 and 1    

         for(i=2;i<n;++i) //loop starts from 2 because 0 and 1 are already printed    

         {    

          a=m+flag;    

          Console.Write(a+" ");    

          m=flag;    

          flag=a;    

         }    

                 }

                 break;

             case 3:

                 {

                       flag=1;

       Console.Write("Enter any Number: ");      

       n= int.Parse(Console.ReadLine());     

       for(i=1;i<=n;i++){      

        flag=flag*i;      

       }      

       Console.Write("Factorial of " +n+" is: "+flag); 

                 }

                 break;

     }  

   }

  }